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Fuel efficiency of the Austrian passenger vehicle fleet—Analysis of trends in the technological profile and related impacts on CO2 emissions
ARTICLE IN PRESS Energy Policy 37 (2009) 3779–3789
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Fuel efficiency of the Austrian passenger vehicle fleet—Analysis of trends in the technological profile and related impacts on CO2 emissions I. Meyer , S. Wessely Austrian Institute of Economic Research (WIFO), P.O. Box 91, 1103 Vienna, Austria
a r t i c l e in fo
abstract
Article history: Received 18 March 2009 Accepted 15 July 2009 Available online 3 August 2009
This paper analyzes trends in the technological profile of the Austrian personnel vehicle fleet from 1990 to 2007. This includes the parameters of power, engine size and weight, which beyond the technological efficiency of the motor engine itself, are considered to be the main determinants of the fuel efficiency of the average car stock. Investigating the drivers of ever rising transport related greenhouse gas emissions is crucial in order to derive policies that strive towards more energy-efficient on-road passenger mobility. We focus on the efficacy of technological efficiency improvements in mitigating climaterelevant emissions from car use in light of shifting demand patterns towards bigger, heavier and more powerful cars. The analysis is descriptive in nature and based on a bottom-up database that was originally collated for the purpose of the present study. Technological data on car models, which includes tested fuel consumption, engine size, power and weight, is related to registered car stock and, in parts, to newly registered cars. From this, we obtain an original database of the Austrian passenger car fleet, i.e. information on consumer choice of specific car models, segregated by gasoline and diesel fuelled engines. Conclusions are derived for policies aimed at reducing the fossil fuel consumption of the moving vehicle fleet in order to contribute to a low carbon society. & 2009 Elsevier Ltd. All rights reserved.
Keywords: Passenger car fleet Fuel efficiency Climate policy
1. Introduction The Austrian transport sector is one of the greatest energy consuming sectors releasing a key share of about a quarter (27.6%) of all energy related greenhouse gas (GHG) emissions and 32.4% of CO2 emissions in 2007 (Anderl et al., 2009).1 In Austria, as in the majority of EU countries, GHG emissions are currently rising most rapidly in the transport sector. Between 1990 and 2007 CO2 emissions from transport rose by 74% amounting to 23.9 million tonnes of CO2 in 2007, with on-road traffic contributing around 95% of the transport related CO2 budget (see Fig. 1). Passenger cars were the dominant source of emissions within the period, causing 53.0% while commodity freight trucks released about 42% of CO2 emissions. The remaining 5.0% could be attributed to inland water, air and pipeline transports. However, emissions and transport patterns have also shifted considerably within the observation period. While the share of freight traffic related CO2 emissions climbed from 30.6% in 1990 to 42% in 2007, the share of passenger car related emissions dropped from 63.3% to a share of 53.0% in 2007, while remaining the greater source of emissions.
Corresponding author. Tel.: +43 1798 93 86 250.
E-mail address: [email protected] (I. Meyer). In 2007, the industry contributed 29.1% of GHG and 21. 2% of CO2 emissions. The remaining emissions originated in households, services, agriculture and waste. 1
0301-4215/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2009.07.011
The level and dynamics of transport related CO2 emissions challenge national (and international) climate policies. Other energy consuming sectors are struggling to abate emissions themselves. Therefore, they are unable to compensate for an increase in transport related emissions and it is imperative for the transport sector to contribute to overall emissions mitigation. If not, transport with its dynamic growth and limited possibilities for fuel switching could undermine improvements in other sectors. The significance of the passenger car sector as a source of CO2 emissions is also of particular importance with regard to developing and transition countries where the greatest increase in global passenger car related emissions is expected to take place in the near future (WBCSD, 2004; Meyer et al., 2007) This is due to accelerating industrialization, income growth, urbanization, rapid population growth and accompanying increased transport needs and wants. Studying the impact of Austrian consumer purchase patterns with respect to cars, along with their technological endowments and consequences for average vehicle fleet fuel efficiency, is therefore of strategic importance for future sectoral policies in the passenger car sector in both industrialized and transition economies. This paper analyzes the evolving technological profile of the Austrian passenger car fleet from 1990 to 2007. Studying the determinants of passenger car related emissions is crucial to responding to the challenge of ever rising emissions in this sector. The main determinants of car related CO2 emissions are the level
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Fig. 1. Transport-related CO2 emissions in Austria 1990–2007, (Anderl et al., 2009).
of car ownership, the pattern of vehicle use and the technical performance of the vehicle fleet, i.e. consumer choice of specific car models that together shape the scope of vehicle fleet fuel efficiency. This encompasses both behavioural aspects and technological characteristics. The focus of this study is the analysis of the technical parameters of registered passenger cars, how they have evolved over time and what kind of impact they generate in terms of fuel efficiency and corresponding CO2 emissions, given a specific level of car ownership and travel behaviour. For this purpose, we have developed an original database on Austrian registered car models and collated information on the equivalent technical characteristics. We provide a detailed representation of the data in Section 2. The database allows us to portray the evolving technological profile of the Austrian vehicle fleet with respect to power, engine size, weight and fuel consumption, differentiated by the type of combustion system, i.e. diesel or gasoline (Section 3). We delineate shifts in demand patterns throughout the observation period and derive time series of the registration weighted average fuel efficiency. Section 4 briefly depicts the development in demand of the newly registered car fleet in terms of power characteristics. Section 5 provides a summary of the results together with conclusions on a more climate-oriented policy with regard to the efficiency of the passenger vehicle fleet.
were calculated for each year in the period, taking into account the highest stock numbers per model, listed downwards until the 60 percentiles were matched. We consider this sample to be representative, yet it is clear that scarcely demanded models offering, for example, high power and speed fall outside the examined sample. As Schipper et al. (1993) have pointed out, this procedure could result in a systematic bias towards an overestimation of the calculated efficiency improvement. However, the bias, if it exists, could not be assessed in detail within the realm of this study. On the basis of the compiled bottom-up database we generate time series of technological characteristics differentiated by gasoline and diesel combustion systems. This information was formerly not available. Only data on the power class segments of registered gasoline and diesel stocks as well as on newly registered cars could be obtained from Statistics Austria for the years 1999–2007. However, these data could not be disaggregated to the level of car models and therefore did not yield detailed technical information. With our databases we are able to present an original data analysis of Austrian car stock. This includes data on personnel light trucks and vans.
2. Data on car stock and technological parameters
3.1. Demand patterns towards combustion systems, power, engine size and weight
For the present study an original database detailing the technological profile of the Austrian passenger car fleet was compiled for the period from 1990 to 2007. This bottom-up database consists, first, of a representation of registered car stock in Austria, comprising a total of 5836 types of registered cars in the year 2007. The data are taken from the annual car stock statistics published by Statistics Austria (2007). Second, each of the registered car models was attributed five technological parameters, i.e. propulsion system, power, weight, cubic capacity and tested fuel consumption. The corresponding information was collated on the basis of the annually published ‘‘Auto Katalog’’ (Motor Presse Stuttgart, 2008), which gathers technical information on world market car models. Information on the five parameters in question could be matched for every vehicle model in the data stock. However, to make our study feasible, we limited our analysis to a representative number of cars, choosing a sample of 60 percent for each year. This reduced the number of car models considered to about 466. The 60 percentiles of the entire car stock
3. The Austrian car stock and its technological profile from 1990 to 2007
Fig. 2 shows the entire Austrian car stock from 1990 to 2007 (left axis) and the average per capita car endowment (right axis) (Statistics Austria, 2007). Car stock rose by an average of 2.1% per year, growing by about 43% within the observation period of 17 years. However, from 2001 to 2002 there is a break in the data time series due to an adjustment in the car stock data. The data from Statistics Austria (2007) represent secondary data obtained from admission offices of car insurers. Given a mismatch between the car stock data from Statistics Austria (2007) and that of the insurance companies, several data sets on depreciated cars out of use had to be adjusted, thereby resulting in reduced Austrian vehicle stock in the year 2002. Comparing average annual growth rates of overall car stock in the period 1990–2001 with that of 2002–2007, we observe a much smaller average growth rate of 1.3% p.a. in the second term compared to a 2.9% average growth rate in the first time period. The slowdown in the growth of the vehicle stock could indicate a satiation in car stock and car
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Fig. 2. Passenger car stock and cars per capita 1990–2007, Statistics Austria, WIFO calculations.
Fig. 3. Demand patterns towards combustion systems: penetration of diesel cars, 1990–2007, Statistics Austria, WIFO.
demand, respectively, given a per capita car endowment of 0.51 in 2007. Austrian per capita car stock is in a comparable range with European neighbor states, i.e. 0.52 in Switzerland, 0.55 in Germany, 0.6 in Italy, 0.49 in France, and 0.42 in the Netherlands (year 2005) (IRF, 2007). Looking at car fleet composition in terms of combustion systems we distinguish gasoline and diesel cars. Hybrid cars, electrical and natural gas cars are still of minor importance, i.e. the number of natural gas and hybrid cars reached 1770 in 2007 compared to 701 in 2006 and the number of electrical cars grew to 131 in 2007 from 127 in 2006, both classes of combustion systems representing 0.0% of the total registered car stock (Kvapil and Reisel, 2008). Fig. 3 shows the shift in demand patterns towards combustion systems, i.e. the continued penetration of diesel cars in the car stock. While the stock of gasoline cars declined at an average annual rate of 1.6%, diesel vehicle stock rose by 10.6% p.a. overshooting gasoline stock in 2005. This being responsible for a shift in the equivalent shares, starting in 1990 with 86% of the vehicle fleet constituted by gasoline cars, they account for only 46% of the stock in 2007. This gives way to a rising trend in diesel cars from 14% in 1990 to 54% in 2007, denoting an emerging
preference towards diesel cars from the beginning of the 1990s. The growing share of diesel cars in passenger car stock is not only an Austrian trend but a European one as well, as examined by Schipper et al. (2002). Thereafter, by 1995 diesels made up almost 26% of the French car fleet, 15% of the West German car fleet, 12% of the Italian and the Dutch car fleet and 11% in the UK, while the Nordic countries showed shares of only 3% and 7%. With a diesel share of about 23% in 1995, Austria ranges in the upper field of the European ‘‘dieselisation’’ trend. According to Schipper et al. (2002), the western European diesel average increased steadily in the 1990s and achieved nearly 30% in 1998. At that time the Austrian share of diesel cars was about 31%. Diesel cars are considered to provide crucial potential for fuel savings and reduced emissions from transport, as diesels consume less energy per kilometer than petrol cars. However, diesels tend to be used more due to the lower fuel prices and lower overall service prices that arise from switching to more fuel-efficient diesel cars. They are also driven more because they tend to be used by more kilometer-intensive drivers, e.g. taxi drivers and sales representatives. The literature cites two main developments that have made diesel cars become more and more attractive
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Fig. 4. Price ratio gasoline over diesel in Euro, 1993–2007, (IEA, 2008).
within segments that were formerly devoted to gasoline engines (Schipper et al., 2002). First, government policies introduced favorable vehicle and fuel taxation for diesels and second, the maturing of diesel vehicle technology steadily increased vehicle and engine options for manufacturers, thereby stimulating the popularity of diesels across all market segments. The sustained growth in diesel stock was thus stimulated by a successful combination of demand pull and supply push policies. Diesel penetration is an excellent practice example for studying the market diffusion of a new combustion system and might therefore assist in the promotion of energy-efficient systems such as hybrids, electric and natural gas cars. For instance, a systematic price incentive in the form of a reduced excise tax on diesel can be ascertained. Fig. 4 shows the differential between the excise tax on diesel and that on gasoline (per liter of fuel), as well as the retail price differential of diesel and gasoline fuels in terms of the gasoline–diesel price ratio from 1993 to 2007. The governmental tax incentive on diesel fuels is a decisive factor of a demand pull strategy towards diesel cars. However, the price differential of gasoline and diesel fuels has diminished since the beginning of the 21 century, showing a decreased interest in the promotion of diesel cars. There are general doubts about the achievements of ‘‘dieselisation’’ in terms of reduced fuel demand and emissions gains because diesels are driven considerably further than petrol cars, thus compensating for their technological efficiency advantage. This is referred to as the ‘‘travel related rebound effect’’. The travel related and price-induced rebound effects are well documented, in particular with respect to the USA where fuel prices and fuel efficiencies of the vehicles are lower than in Europe (see e.g. Greene, 1992; Jones, 1993; Johansson and Schipper, 1997; Greening et al., 2000; Small and Van Dender, 2007). However, there is another rebound in terms of shifting demand patterns towards larger cars (vehicle purchase rebound) that counteracts the technical efficiency advantage of dieselisation and engine progress. We investigate this subject matter by carrying out a descriptive analysis of shifts in demand patterns with respect to registered car stock in terms of power class categories measured in kilowatts (kW), engine size measured in cubic centimeters (ccm) and the weight of an average car measured in kilograms (kg). These technological parameters are significant determinants
of specific fuel consumption and, thus, drivers of the fuel efficiency of the registration weighted car fleet. Fig. 5 depicts the development of power classes differentiated by diesel (Xd) and gasoline (Xg) cars according to lower power classes (up to 60 kW), middle power classes (from 60 to 80, to 100 kW) and superior power classes (greater than 100 kW). There is a clear shift in preference towards middle power class diesels of 60–80 kW, showing a substantial average annual increase of 23% amounting to plus 3319% within the observation period. This growth was even overshot by the subsequent diesel power class of 80–100 kW that rose by 30% p.a. (+3796%) in registered cars from 1993 to 2007, albeit starting at very low level. The smaller diesel class of 40–60 kW also grew at a substantial rate by almost 11% p.a. (plus 450%), as did the superior power class of plus 100 kW, which grew by about 15% p.a. (plus 1364%) within the last 9 years of the observation period. These developments clearly show an emerging mass market for diesel cars in mid-size to large car segments. In contrast, gasoline car stock shrank in absolute terms in all power class segments, in particular with respect to the lowest power class of up to 40 kW ( 54%, 4.5% p.a.) and regarding the power class 80 to 100 kW ( 67%, 6.4% p.a.). The middle class segments also declined by 2.4% p.a. ( 34%) in the 40–60 kW class and 1.9% p.a. ( 28%) in the 60–80 kW class. Fig. 6 captures the development of demand patterns towards the technical parameter engine size measured in cubic capacity (cubic centimeters, ccm), where we can observe a shift of demand patterns towards higher engine sizes. The range of 1400–2000 ccm of diesel cars has grown most strongly, with an average annual growth rate of about 14% (+806%). The next higher diesel engine size of over 2000 ccm grew at a similar rate, i.e. by 14% p.a. amounting to +824% in the observation period. There is a trend in purchase patterns of diesel cars towards middle engine size, while in the gasoline domain the reduction of small engine size vehicles was slower than the middle engine car class, i.e. 6% p.a. ( 66%) in the 2000 ccm plus class, 5% p.a. ( 59%) in the middle engine class and 1.4% ( 21%) in the lower engine class of fewer than 1400 ccm. This development may be due to the fact that more diesels have been offered in the mid-size to large car segments than in the small car segments (Schipper et al., 2002). Thus, gasoline cars remain dominant in the smaller engine class.
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Fig. 5. Development of power clusters of diesels and gasoline cars, 60 percentiles of car stock, 1990–2007, WIFO database.
Fig. 6. Development of engine size of diesels and gasoline cars, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 7 depicts the weight development of an average registration weighted diesel and gasoline car. The growth in weight of an average car is also calculated on the registration weighted basis. It appears there is a trend in demand patterns towards higher car weights, driven also by the increase in demand for diesel cars that are generally heavier than gasoline fuelled cars. Diesel cars are gaining weight at an average of 1.6% per year, while gasoline cars are increasing in weight by only 0.8% on average per year. In total, we observe an average annual increase of 1.6% in average registration weighted car weight, which amounts to an increase in weight of 32% within the observed period of 1990–2007. Car weight can be seen as a proxy for factors such as comfort, safety or carrying capacity. However, additional factors are involved. A study by Jacobson and McLay (2006) estimates the impact of higher average passenger (driver and non-driver) weight during the period from 1960 to 2002 on automobile fuel consumption in the United States. They calculate an annual additional fuel use of 39 million gallons of fuel for each
additional pound of average passenger weight. While obesity has become a major public health problem, efforts to reduce car weight mainly concentrate on research into optimal materials for car frame production. This is considered more important as innovations in motor engines have been saturated. An indicator of efficiency showing the relation of fuel consumption to car weight is delineated in the next section. 3.2. Trend of fuel efficiency of the car fleet Fig. 8 captures the development of the registration weighted fuel efficiency of the Austrian car fleet measured in liters of fuel used per 100 km, differentiated by diesels, gasoline cars and a diesel-equivalent aggregate. The latter is measured by the energy content of the fuels. The analysis is based on manufacturers’ data on new models of fuel consumption (Motor Presse Stuttgart, 2008). While the diesel car fleet shows an average improvement
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Fig. 7. Development of registration weighted car weight of diesels and gasoline cars, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 8. Development of fuel efficiency of the Austrian car fleet by registration weighted fuel consumption, 60 percentiles of car stock 1990–2007, WIFO database.
in fuel efficiency of 1.03% per year, the gasoline car fleet is gaining efficiency improvements by 1.56% on average per year. This amounts to a reduction in fuel consumption per 100 km driven by 16% for diesels and 23.7% for gasoline cars within the observed time period. Registration weighted fuel use was therefore reduced from an average of 7.1 l/100 km to about 6 l/100 km within the diesel fleet and from an average of 9.1 l/100 km to 7 l/100 km within the gasoline fleet. For the total fleet, this results in a reduced diesel-equivalent fuel use of approximately 2 l/100 km within 17 years, resulting in an average annual reduction in fuel use of 1.67% considering the registration weighted car stock. This is a remarkable gain in fuel efficiency taking into account comparable developments from the literature. The OECD and IEA (2001), for example, indicates a gain in fuel efficiency of 1 l of fuel use per 100 km for on-road car stock within 20 years in Germany. The fuel efficiency indicator is translated into grams of CO2 emitted per kilometer driven on the basis of the IPCC standards. Thereafter, in 2007 the average registration weighted car fleet shows 163 g CO2/km for a diesel-equivalent car, 160 g CO2/km for an average diesel car and 165 g CO2/km for an average gasoline car. Fig. 9 shows the development of the average CO2 emissions of the two car fleets as well as a diesel-to-gasoline relationship. The
latter shows a declining efficiency gap between diesel and gasoline cars. One of the implications that can be drawn from this result is that there appears to be a substantial improvement in the average fuel efficiency of registered car stock, despite market shifts towards heavier cars with greater engine size and higher power. Subsequently, we conduct an analysis of the development in fuel efficiency of three different power classes (see Figs. 10 and 11). Within the diesel car stock the highest efficiency gains were realized in the high power car class of 60–80 kW, amounting to an average annual increase in fuel efficiency of 2.4% compared to the middle power class, which showed an increase in efficiency of 1.5%, and the lower class, which lacked efficiency gains at an average annual increase of only 0.3%. Overall, efficiency improvements came to a halt towards the end of the century. What is striking is that smaller power classes show higher average fuel consumption, i.e. the 40–60 kW class shows higher fuel consumption between 1994 and 2003 than the 60–80 kW class, and the lower than 40 kW class shows a higher average fuel consumption than the other two clusters from 1999 onwards. The fact that cars with lower engine power use more fuel can be explained by the practice of curtailing engine power to profit from a lower motor vehicle tax. As motor vehicle tax is calculated on the basis of power classes, there is an intrinsic incentive to reduce
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Fig. 9. Development of average registration weighted CO2 per kilometer, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 10. Development of fuel efficiency of diesel cars clustered by power, 60 percentiles of car stock 1990–2007, WIFO database.
engine power, resulting in significantly higher average fuel consumption. The picture looks slightly different for gasoline car stock (see Fig. 11). Here, fuel efficiency improvements are of the same order of magnitude throughout the three power clusters, ranging from around 1.6% in the lowest class to 1.8% in the highest power class. However, calculations of the fuel efficiency of car fleets based on new car data supplied by manufacturers have been criticized as underestimating the fuel consumption of real-world driving (Schipper and Tax, 1994). This is because test cycles that measure fuel use and CO2 emissions, e.g. the New European Driving Cycle (NEDC) implemented in the EU since January 1996, do not match specific driving profiles, in particular where short distances, urban driving or high-speed motorway driving are the dominant modes of car use. Therefore, assessments of real-world car driving and fuel consumption in relation to test cycle based manufacturer data reveal underestimations in fuel consumption from the test cycles of about 15–25% (Schipper and Tax, 1994). The Austrian Association of Consumer Information has tested several cars, finding a discrepancy between test cycle based and real-world based fuel
consumption of between 3.6% and 29% (Konsument, 2008). The greater discrepancy results from a small size car type (Smart) driven on a motorway test cycle that is not part of the official NEDC. As this car type is not suitable for higher velocities this test of real-world conditions actually significantly drives up CO2 emissions. In general, test cycles used by manufacturers nevertheless provide information on annual improvements in fuel efficiency and are therefore suitable as a comprehensive indicator of technical change. In order to give a representation of the gap between test cycle based measures of fuel efficiency and real-world driving fuel consumption, we have assessed the scope of the gap for the year 2007 using data from the ‘‘spritmonitor’’ web portal.2 The ‘‘spritmonitor’’ portal collects data on fuel consumption clustered into kW power classes from real-world drivers who engage in data collection. As this web portal does not supply time-related data we have limited the assessment to the year 2007. Based on the
2
http://www.spritmonitor.de/de/leistung_kontra_verbrauch.html.
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Fig. 11. Development of fuel efficiency of gasoline cars clustered by power, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 12. Indicator of (thermodynamic) efficiency: fuel use per kg weight, 60 percentiles of car stock 1990–2007, WIFO database.
data from this year, real-world fuel consumption within registration weighted gasoline car stock is about 1.9% higher than that based on test cycle information. Within diesel registration weighted vehicle stock the discrepancy lies at +5.1% and the diesel-equivalent calculation reveals a real-world fuel consumption which is 3.83% higher than that based on the test cycle. This indicates a smaller range of divergence between actual and theoretical fuel efficiency than the numbers cited above. Presenting another aspect in the fuel efficiency of the Austrian car fleet, an indicator of efficiency in terms of fuel consumption in liters per kg weight of car is presented in Fig. 12. This indicator is known to represent the thermodynamic efficiency of the average car or car stock, i.e. the efficiency of the conversion device. Higher efficiency means that more moving mass is obtained from the same heat content or the same fuel input. Fig. 12 reveals an overall trend towards more efficient cars. In 1990 an average car required 0.008 l of diesel-equivalent fuel to move one kilogram for 100 km. This number has been reduced to 0.005 l per kg in 2007, indicating an increase in thermodynamic efficiency of about 43%. Gasoline-driven
cars improve annually by about 2.35% on registration weighted average while diesel cars show a slightly better annual improvement of 2.56%. When calculating on the basis of diesel-equivalents we obtain a thermodynamic advancement of 3.24% per year. Diesel cars are thermodynamically more efficient than gasoline cars due to the higher heat content of diesel. The shift in the diesel-equivalent efficiency graph towards the diesel line again represents the switch in propulsion systems towards diesel cars. Compared to improvements in fuel consumption per 100 km driven (see Fig. 8), the annual improvement of the thermodynamic efficiency is higher. One of the reasons for the smaller improvement in fuel consumption is that some of the efficiency gains are compensated for by the use of heavier cars. Hence, pure technical efficiency gain has partly been offset by a shift in market demand towards bigger cars. What are the combined influences of the derived fuel efficiencies of the diesel and gasoline fleets, their stock numbers and average vehicle kilometers travelled in terms of CO2 emissions? Using technical registration weighted fuel consumption we calculate the fleet-specific CO2 emissions budgets on the
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Fig. 13. Evolution of CO2emission budgets by diesel and gasoline car fleets, WIFO database, Odyssee database.
basis of data on average vehicle kilometers travelled found in the Odyssee database (see Fig. 13)3. It should be noted that the Odyssee data on average kilometers driven by diesel and gasoline cars constitute model-adjusted data and, thus, may not be considered ‘‘real’’ data in terms of survey-derived data. However, given the fact there are no other data available we calculate the car fleets emissions budgets on the basis of this source. In light of this caveat, the necessity of conducting surveys to elicit the ‘‘real’’ volume of vehicle kilometers travelled by diesel and gasoline cars in order to improve research results shall be emphasized. Comparing the shares of the diesel stock fleet (3) with CO2 emissions shares, we find a gap in terms of higher emissions shares despite the better fuel efficiency of diesel cars. Thus, higher average distances driven by diesel cars over-compensate for improved fuel efficiency. In turn, the gasoline fleet shows an under-proportionate emissions share with regard to its stock fleet share and its lesser fuel efficiency. Based on this analysis, we ascertain a travel induced rebound effect for diesel cars due to a lower service price. This trend may well signal the beginning of a continuously declining diesel share in the total vehicle fleet.
cars indicate a continuing trend towards a demand of higher power classes with respect to diesels. Among diesel cars all clusters showed lower registration figures, with the exception of the over 100 kW power class. This cluster rose by 445%, amounting to an annual growth of 23.6%. Given the ongoing preference for higher power classes there is a persistent trend towards the offsetting of technological efficiency gains. With respect to gasoline cars, which showed lower registration except for the 40–60 kW and the 60–80 kW clusters, we find growth of 4% (0.5% p.a.) and 33.6% (3.7% p.a.), respectively, confirming that gasoline cars are still the preferred small size cars. In total, growth in the number of newly registered cars has come to a halt. From 2002 to 2007 the newly registered car fleet grew by 6.3% at an average annual rate of 1.2%. For the entire observation period, we find growth in the newly registered car fleet to be negative at 5.4%. Finally, a trend reversal in the registration of gasoline and diesel cars can be observed, i.e. the share of diesel has diminished, while that of gasoline cars has grown among newly registered cars. This is due to the lower gap in fuel prices and tax incentives for diesels and to the fact that diesels must be equipped with particle filters that are costly and not suitable for short distance driving.
4. Trend of fuel efficiency of newly registered cars Improvements in new car fuel efficiency should gradually translate into improvements in the fuel consumption of the overall vehicle fleet. The speed at which this takes place depends upon the ratio of new registrations to car stock numbers and on the rate of stock turnover. Analyzing trends in the fuel efficiency of newly registered cars is therefore a good indication of the outlook of average car stock fuel efficiency. However, as the scope of the present study was limited with respect to time and budget, we have not been able to collate the data to present a detailed technological profile of newly registered cars as we did for the passenger car stock. However, data on the newly registered car fleet differentiated by diesel and gasoline as well as by power clusters from 1999 to 2007 (as depicted in Fig. 14) could be obtained from Statistics Austria. The figures for newly registered 3
http://www.odyssee-indicators.org.
5. Conclusions Our study reveals that the Austrian registered vehicle fleet demonstrates a substantial improvement in average registration weighted fuel efficiency. Specifically, fuel consumption was reduced by an annual average of 1.67% which is equal to an increase in fuel efficiency of +25% within the observation period of 1990–2007. This denotes a remarkable reduction in fuel intensity which took place despite a delineated market shift towards heavier cars with greater engine size and higher power capacity. These trends in demand were responsible for partially offsetting potential efficiency gains that could have otherwise been achieved through engine technology improvements and dieselisation (vehicle purchase rebound effect). Dieselisation and technical change, in turn, neutralized the effects from the vehicle purchase rebound towards higher fuel-consuming cars. Finally, the efficiency gains of the average car fleet could have been more
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Fig. 14. Development of newly registered cars by fuel use and power 1999–2007, Statistics Austria.
pronounced without the counteracting shifts in demand patterns towards bigger and heavier cars. However, dieselisation brought about a higher average distance driven per car and, thus, finally over-compensated for diesel-based technological efficiency advantages in terms of vehicle fleet CO2 emissions. Policies that strive to reduce passenger car related CO2 emissions therefore need to address both the promotion of a low carbon passenger car fleet and a reduction in average vehicle kilometers travelled by diesels in order to take full advantage of the diesel efficiency advantage. Policies therefore have to set clear incentives towards the purchase of low fossil fuel consuming cars and neutralize financial incentives on diesel fuels. Based on the trend in dieselisation it is evident that the penetration of a new fuel efficiency system, i.e. of diesel cars, was successfully promoted by demand pull and technology push stimuli. Therefore, we recommend that transport policies opt for favorable vehicle and fuel taxation on low carbon passenger vehicles, e.g. highly fuel-efficient diesel and gasoline, electric, hybrids and natural gas cars. Such policies are to be based on the carbon content of distance driven. Austria has carried out an initial reform of its tax levied upon the first registration of passenger cars in July 2008.4 However, the incentives have to be enhanced in order to swiftly promote a decarbonisation of the Austrian vehicle fleet, i.e. the motor vehicle tax must recur to the average fuel consumption and not to the power class of the car. At the same time a technology push strategy should take care of the necessary supply of low carbon energy-efficient passenger vehicles. Given the positive trend in the average fuel efficiency of the Austrian passenger car fleet, together with the rising trend in passenger car related CO2 emissions, it is clear that the ever rising emissions must be due to the increase in vehicle stock and volume of kilometers travelled. Policies that aim to reduce passenger transport related emissions must therefore also
4 The Normverbrauchsabgabe (NoVa) introduced a tax incentive on cars that emit fewer than 120 g CO2/km. These cars receive a maximum bonus of 300 Euro while cars emitting more than 180 g CO2/km have to pay a penalty of 25 Euros for each gramme emitted in excess of 180 g CO2/km (160 g CO2/km as of 1 January 2010). Alternative fuel vehicles attract a bonus of a maximum of 500 Euros.
counteract the reduced service prices of passenger car use due to efficiency gains.
Acknowledgements We would like to thank K. Kratena for excellent research assistance and W. Puwein for valuable comments. We gratefully acknowledge helpful comments and suggestions from the editor. We would also like to thank P. Daubitz for expert information on technical parameters of car models and on relevant data sources, ¨ K. Koberl for help with data management and B. Novotny for her assistance in operating database software. Financial support from ¨ sterreichische ¨ the Jubilaumsfonds of the Austrian National Bank (O Nationalbank, Project no. 207) is gratefully acknowledged. References ¨ Anderl, M., Freudenschuß, A., Kother, T., Muik, B., Pazdemik, K., Poupa, S., Schodl, B., Weiss, P., Wieser, M., 2009. Austria’s annual greenhouse gas inventory 1990–2007. Vol. Report REP-0187. Umweltbundesamt, Vienna. Greene, D.L., 1992. Vehicle use and fuel economy: how big is the ‘‘rebound’’ effect?. Energy Journal 13 (1), 117–143. Greening, L.A., Greene, D.L., Difiglio, C., 2000. Energy efficiency and consumption – the rebound effect – a survey. Energy Policy 28 (6–7), 389–401. IEA (Ed.), IEA Statistics, Energy Prices & Taxes, vol. First Quarter. International Energy Agency, Paris. IRF (Ed.), 2007. World Road Statistics 2007, Data 2000–2005. International Road Federation, Geneva. Jacobson, S., McLay, L., 2006. The economic impact of obesity on automobile fuel consumption. The Engineering Economisst 51 (4), 307–323. Johansson, O., Schipper, L., 1997. Measuring long-run automobile fuel demand: separate estimations of vehicle stock, mean fuel intensity, and mean annual driving distance. Journal of Transport Economics and Policy 31 (3), 277–292. Jones, C.T., 1993. Another look at U.S. passenger vehicle use and the rebound effect from improved fuel efficiency. Energy Journal 14 (4), 99–110. Konsument, 2008 July. Jenseits der wirklichkeit. Konsument (7), 1–19. Kvapil, B., Reisel, J., 2008 May. Kraftfahrzeug bestand 2007. Statistische Nachrichten, 404–417. Meyer, I., Leimbach, M., Jaeger, C., 2007 December. International passenger transport and climate change: a sector analysis in car demand and associated CO2 emissions from 2000 to 2050. Energy Policy 35 (12), 6332–6345.
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Motor Presse Stuttgart (Ed.), 2008. Auto Katalog, Das Modellangebot Weltweit 51 ed. Motor Presse Stuttgart, Stuttgart (several editions (1979–2008)). OECD, IEA (Eds.), 2001. Saving Oil and Reducing CO2 Emissions in TransportOptions and Strategies. Organisation for Economic Co-operation and Development. International Energy Agency. Schipper, L., Figueroa, M., Price, L., Espey, M., 1993. Mind the gap: the vicious circle of measuring automobile fuel use. Energy Policy 21 (12), 1173–1190. Schipper, L., Marie-Lilliu, C., Fulton, L., 2002 May. Diesels in Europe, analysis of characteristics, usage patterns, energy savings and CO2 emission implications. Journal of Transport Economics and Policy 36 (2), 305–340.
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Schipper, L., Tax, W., 1994. New car test and actual fuel economy: yet another gap?. Transport Policy 1 (4), 257–265. Small, K., Van Dender, K., 2007. Fuel efficiency and motor vehicle travel: the declining rebound effect. The Energy Journal 28 (1), 25–51. Statistics Austria (Ed.), 2007. Statistik der Kraftfahrzeuge. Statistik Austria, Vienna (Several editions (1991–2008)). WBCSD (Ed.), 2004. Mobility 2030: Meeting the Challenges to Sustainability. The Sustainable Mobility Project. World Business Council for Sustainable Development, Switzerland.
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Fuel efficiency of the Austrian passenger vehicle fleet—Analysis of trends in the technological profile and related impacts on CO2 emissions I. Meyer , S. Wessely Austrian Institute of Economic Research (WIFO), P.O. Box 91, 1103 Vienna, Austria
a r t i c l e in fo
abstract
Article history: Received 18 March 2009 Accepted 15 July 2009 Available online 3 August 2009
This paper analyzes trends in the technological profile of the Austrian personnel vehicle fleet from 1990 to 2007. This includes the parameters of power, engine size and weight, which beyond the technological efficiency of the motor engine itself, are considered to be the main determinants of the fuel efficiency of the average car stock. Investigating the drivers of ever rising transport related greenhouse gas emissions is crucial in order to derive policies that strive towards more energy-efficient on-road passenger mobility. We focus on the efficacy of technological efficiency improvements in mitigating climaterelevant emissions from car use in light of shifting demand patterns towards bigger, heavier and more powerful cars. The analysis is descriptive in nature and based on a bottom-up database that was originally collated for the purpose of the present study. Technological data on car models, which includes tested fuel consumption, engine size, power and weight, is related to registered car stock and, in parts, to newly registered cars. From this, we obtain an original database of the Austrian passenger car fleet, i.e. information on consumer choice of specific car models, segregated by gasoline and diesel fuelled engines. Conclusions are derived for policies aimed at reducing the fossil fuel consumption of the moving vehicle fleet in order to contribute to a low carbon society. & 2009 Elsevier Ltd. All rights reserved.
Keywords: Passenger car fleet Fuel efficiency Climate policy
1. Introduction The Austrian transport sector is one of the greatest energy consuming sectors releasing a key share of about a quarter (27.6%) of all energy related greenhouse gas (GHG) emissions and 32.4% of CO2 emissions in 2007 (Anderl et al., 2009).1 In Austria, as in the majority of EU countries, GHG emissions are currently rising most rapidly in the transport sector. Between 1990 and 2007 CO2 emissions from transport rose by 74% amounting to 23.9 million tonnes of CO2 in 2007, with on-road traffic contributing around 95% of the transport related CO2 budget (see Fig. 1). Passenger cars were the dominant source of emissions within the period, causing 53.0% while commodity freight trucks released about 42% of CO2 emissions. The remaining 5.0% could be attributed to inland water, air and pipeline transports. However, emissions and transport patterns have also shifted considerably within the observation period. While the share of freight traffic related CO2 emissions climbed from 30.6% in 1990 to 42% in 2007, the share of passenger car related emissions dropped from 63.3% to a share of 53.0% in 2007, while remaining the greater source of emissions.
Corresponding author. Tel.: +43 1798 93 86 250.
E-mail address: [email protected] (I. Meyer). In 2007, the industry contributed 29.1% of GHG and 21. 2% of CO2 emissions. The remaining emissions originated in households, services, agriculture and waste. 1
0301-4215/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2009.07.011
The level and dynamics of transport related CO2 emissions challenge national (and international) climate policies. Other energy consuming sectors are struggling to abate emissions themselves. Therefore, they are unable to compensate for an increase in transport related emissions and it is imperative for the transport sector to contribute to overall emissions mitigation. If not, transport with its dynamic growth and limited possibilities for fuel switching could undermine improvements in other sectors. The significance of the passenger car sector as a source of CO2 emissions is also of particular importance with regard to developing and transition countries where the greatest increase in global passenger car related emissions is expected to take place in the near future (WBCSD, 2004; Meyer et al., 2007) This is due to accelerating industrialization, income growth, urbanization, rapid population growth and accompanying increased transport needs and wants. Studying the impact of Austrian consumer purchase patterns with respect to cars, along with their technological endowments and consequences for average vehicle fleet fuel efficiency, is therefore of strategic importance for future sectoral policies in the passenger car sector in both industrialized and transition economies. This paper analyzes the evolving technological profile of the Austrian passenger car fleet from 1990 to 2007. Studying the determinants of passenger car related emissions is crucial to responding to the challenge of ever rising emissions in this sector. The main determinants of car related CO2 emissions are the level
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Fig. 1. Transport-related CO2 emissions in Austria 1990–2007, (Anderl et al., 2009).
of car ownership, the pattern of vehicle use and the technical performance of the vehicle fleet, i.e. consumer choice of specific car models that together shape the scope of vehicle fleet fuel efficiency. This encompasses both behavioural aspects and technological characteristics. The focus of this study is the analysis of the technical parameters of registered passenger cars, how they have evolved over time and what kind of impact they generate in terms of fuel efficiency and corresponding CO2 emissions, given a specific level of car ownership and travel behaviour. For this purpose, we have developed an original database on Austrian registered car models and collated information on the equivalent technical characteristics. We provide a detailed representation of the data in Section 2. The database allows us to portray the evolving technological profile of the Austrian vehicle fleet with respect to power, engine size, weight and fuel consumption, differentiated by the type of combustion system, i.e. diesel or gasoline (Section 3). We delineate shifts in demand patterns throughout the observation period and derive time series of the registration weighted average fuel efficiency. Section 4 briefly depicts the development in demand of the newly registered car fleet in terms of power characteristics. Section 5 provides a summary of the results together with conclusions on a more climate-oriented policy with regard to the efficiency of the passenger vehicle fleet.
were calculated for each year in the period, taking into account the highest stock numbers per model, listed downwards until the 60 percentiles were matched. We consider this sample to be representative, yet it is clear that scarcely demanded models offering, for example, high power and speed fall outside the examined sample. As Schipper et al. (1993) have pointed out, this procedure could result in a systematic bias towards an overestimation of the calculated efficiency improvement. However, the bias, if it exists, could not be assessed in detail within the realm of this study. On the basis of the compiled bottom-up database we generate time series of technological characteristics differentiated by gasoline and diesel combustion systems. This information was formerly not available. Only data on the power class segments of registered gasoline and diesel stocks as well as on newly registered cars could be obtained from Statistics Austria for the years 1999–2007. However, these data could not be disaggregated to the level of car models and therefore did not yield detailed technical information. With our databases we are able to present an original data analysis of Austrian car stock. This includes data on personnel light trucks and vans.
2. Data on car stock and technological parameters
3.1. Demand patterns towards combustion systems, power, engine size and weight
For the present study an original database detailing the technological profile of the Austrian passenger car fleet was compiled for the period from 1990 to 2007. This bottom-up database consists, first, of a representation of registered car stock in Austria, comprising a total of 5836 types of registered cars in the year 2007. The data are taken from the annual car stock statistics published by Statistics Austria (2007). Second, each of the registered car models was attributed five technological parameters, i.e. propulsion system, power, weight, cubic capacity and tested fuel consumption. The corresponding information was collated on the basis of the annually published ‘‘Auto Katalog’’ (Motor Presse Stuttgart, 2008), which gathers technical information on world market car models. Information on the five parameters in question could be matched for every vehicle model in the data stock. However, to make our study feasible, we limited our analysis to a representative number of cars, choosing a sample of 60 percent for each year. This reduced the number of car models considered to about 466. The 60 percentiles of the entire car stock
3. The Austrian car stock and its technological profile from 1990 to 2007
Fig. 2 shows the entire Austrian car stock from 1990 to 2007 (left axis) and the average per capita car endowment (right axis) (Statistics Austria, 2007). Car stock rose by an average of 2.1% per year, growing by about 43% within the observation period of 17 years. However, from 2001 to 2002 there is a break in the data time series due to an adjustment in the car stock data. The data from Statistics Austria (2007) represent secondary data obtained from admission offices of car insurers. Given a mismatch between the car stock data from Statistics Austria (2007) and that of the insurance companies, several data sets on depreciated cars out of use had to be adjusted, thereby resulting in reduced Austrian vehicle stock in the year 2002. Comparing average annual growth rates of overall car stock in the period 1990–2001 with that of 2002–2007, we observe a much smaller average growth rate of 1.3% p.a. in the second term compared to a 2.9% average growth rate in the first time period. The slowdown in the growth of the vehicle stock could indicate a satiation in car stock and car
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Fig. 2. Passenger car stock and cars per capita 1990–2007, Statistics Austria, WIFO calculations.
Fig. 3. Demand patterns towards combustion systems: penetration of diesel cars, 1990–2007, Statistics Austria, WIFO.
demand, respectively, given a per capita car endowment of 0.51 in 2007. Austrian per capita car stock is in a comparable range with European neighbor states, i.e. 0.52 in Switzerland, 0.55 in Germany, 0.6 in Italy, 0.49 in France, and 0.42 in the Netherlands (year 2005) (IRF, 2007). Looking at car fleet composition in terms of combustion systems we distinguish gasoline and diesel cars. Hybrid cars, electrical and natural gas cars are still of minor importance, i.e. the number of natural gas and hybrid cars reached 1770 in 2007 compared to 701 in 2006 and the number of electrical cars grew to 131 in 2007 from 127 in 2006, both classes of combustion systems representing 0.0% of the total registered car stock (Kvapil and Reisel, 2008). Fig. 3 shows the shift in demand patterns towards combustion systems, i.e. the continued penetration of diesel cars in the car stock. While the stock of gasoline cars declined at an average annual rate of 1.6%, diesel vehicle stock rose by 10.6% p.a. overshooting gasoline stock in 2005. This being responsible for a shift in the equivalent shares, starting in 1990 with 86% of the vehicle fleet constituted by gasoline cars, they account for only 46% of the stock in 2007. This gives way to a rising trend in diesel cars from 14% in 1990 to 54% in 2007, denoting an emerging
preference towards diesel cars from the beginning of the 1990s. The growing share of diesel cars in passenger car stock is not only an Austrian trend but a European one as well, as examined by Schipper et al. (2002). Thereafter, by 1995 diesels made up almost 26% of the French car fleet, 15% of the West German car fleet, 12% of the Italian and the Dutch car fleet and 11% in the UK, while the Nordic countries showed shares of only 3% and 7%. With a diesel share of about 23% in 1995, Austria ranges in the upper field of the European ‘‘dieselisation’’ trend. According to Schipper et al. (2002), the western European diesel average increased steadily in the 1990s and achieved nearly 30% in 1998. At that time the Austrian share of diesel cars was about 31%. Diesel cars are considered to provide crucial potential for fuel savings and reduced emissions from transport, as diesels consume less energy per kilometer than petrol cars. However, diesels tend to be used more due to the lower fuel prices and lower overall service prices that arise from switching to more fuel-efficient diesel cars. They are also driven more because they tend to be used by more kilometer-intensive drivers, e.g. taxi drivers and sales representatives. The literature cites two main developments that have made diesel cars become more and more attractive
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Fig. 4. Price ratio gasoline over diesel in Euro, 1993–2007, (IEA, 2008).
within segments that were formerly devoted to gasoline engines (Schipper et al., 2002). First, government policies introduced favorable vehicle and fuel taxation for diesels and second, the maturing of diesel vehicle technology steadily increased vehicle and engine options for manufacturers, thereby stimulating the popularity of diesels across all market segments. The sustained growth in diesel stock was thus stimulated by a successful combination of demand pull and supply push policies. Diesel penetration is an excellent practice example for studying the market diffusion of a new combustion system and might therefore assist in the promotion of energy-efficient systems such as hybrids, electric and natural gas cars. For instance, a systematic price incentive in the form of a reduced excise tax on diesel can be ascertained. Fig. 4 shows the differential between the excise tax on diesel and that on gasoline (per liter of fuel), as well as the retail price differential of diesel and gasoline fuels in terms of the gasoline–diesel price ratio from 1993 to 2007. The governmental tax incentive on diesel fuels is a decisive factor of a demand pull strategy towards diesel cars. However, the price differential of gasoline and diesel fuels has diminished since the beginning of the 21 century, showing a decreased interest in the promotion of diesel cars. There are general doubts about the achievements of ‘‘dieselisation’’ in terms of reduced fuel demand and emissions gains because diesels are driven considerably further than petrol cars, thus compensating for their technological efficiency advantage. This is referred to as the ‘‘travel related rebound effect’’. The travel related and price-induced rebound effects are well documented, in particular with respect to the USA where fuel prices and fuel efficiencies of the vehicles are lower than in Europe (see e.g. Greene, 1992; Jones, 1993; Johansson and Schipper, 1997; Greening et al., 2000; Small and Van Dender, 2007). However, there is another rebound in terms of shifting demand patterns towards larger cars (vehicle purchase rebound) that counteracts the technical efficiency advantage of dieselisation and engine progress. We investigate this subject matter by carrying out a descriptive analysis of shifts in demand patterns with respect to registered car stock in terms of power class categories measured in kilowatts (kW), engine size measured in cubic centimeters (ccm) and the weight of an average car measured in kilograms (kg). These technological parameters are significant determinants
of specific fuel consumption and, thus, drivers of the fuel efficiency of the registration weighted car fleet. Fig. 5 depicts the development of power classes differentiated by diesel (Xd) and gasoline (Xg) cars according to lower power classes (up to 60 kW), middle power classes (from 60 to 80, to 100 kW) and superior power classes (greater than 100 kW). There is a clear shift in preference towards middle power class diesels of 60–80 kW, showing a substantial average annual increase of 23% amounting to plus 3319% within the observation period. This growth was even overshot by the subsequent diesel power class of 80–100 kW that rose by 30% p.a. (+3796%) in registered cars from 1993 to 2007, albeit starting at very low level. The smaller diesel class of 40–60 kW also grew at a substantial rate by almost 11% p.a. (plus 450%), as did the superior power class of plus 100 kW, which grew by about 15% p.a. (plus 1364%) within the last 9 years of the observation period. These developments clearly show an emerging mass market for diesel cars in mid-size to large car segments. In contrast, gasoline car stock shrank in absolute terms in all power class segments, in particular with respect to the lowest power class of up to 40 kW ( 54%, 4.5% p.a.) and regarding the power class 80 to 100 kW ( 67%, 6.4% p.a.). The middle class segments also declined by 2.4% p.a. ( 34%) in the 40–60 kW class and 1.9% p.a. ( 28%) in the 60–80 kW class. Fig. 6 captures the development of demand patterns towards the technical parameter engine size measured in cubic capacity (cubic centimeters, ccm), where we can observe a shift of demand patterns towards higher engine sizes. The range of 1400–2000 ccm of diesel cars has grown most strongly, with an average annual growth rate of about 14% (+806%). The next higher diesel engine size of over 2000 ccm grew at a similar rate, i.e. by 14% p.a. amounting to +824% in the observation period. There is a trend in purchase patterns of diesel cars towards middle engine size, while in the gasoline domain the reduction of small engine size vehicles was slower than the middle engine car class, i.e. 6% p.a. ( 66%) in the 2000 ccm plus class, 5% p.a. ( 59%) in the middle engine class and 1.4% ( 21%) in the lower engine class of fewer than 1400 ccm. This development may be due to the fact that more diesels have been offered in the mid-size to large car segments than in the small car segments (Schipper et al., 2002). Thus, gasoline cars remain dominant in the smaller engine class.
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Fig. 5. Development of power clusters of diesels and gasoline cars, 60 percentiles of car stock, 1990–2007, WIFO database.
Fig. 6. Development of engine size of diesels and gasoline cars, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 7 depicts the weight development of an average registration weighted diesel and gasoline car. The growth in weight of an average car is also calculated on the registration weighted basis. It appears there is a trend in demand patterns towards higher car weights, driven also by the increase in demand for diesel cars that are generally heavier than gasoline fuelled cars. Diesel cars are gaining weight at an average of 1.6% per year, while gasoline cars are increasing in weight by only 0.8% on average per year. In total, we observe an average annual increase of 1.6% in average registration weighted car weight, which amounts to an increase in weight of 32% within the observed period of 1990–2007. Car weight can be seen as a proxy for factors such as comfort, safety or carrying capacity. However, additional factors are involved. A study by Jacobson and McLay (2006) estimates the impact of higher average passenger (driver and non-driver) weight during the period from 1960 to 2002 on automobile fuel consumption in the United States. They calculate an annual additional fuel use of 39 million gallons of fuel for each
additional pound of average passenger weight. While obesity has become a major public health problem, efforts to reduce car weight mainly concentrate on research into optimal materials for car frame production. This is considered more important as innovations in motor engines have been saturated. An indicator of efficiency showing the relation of fuel consumption to car weight is delineated in the next section. 3.2. Trend of fuel efficiency of the car fleet Fig. 8 captures the development of the registration weighted fuel efficiency of the Austrian car fleet measured in liters of fuel used per 100 km, differentiated by diesels, gasoline cars and a diesel-equivalent aggregate. The latter is measured by the energy content of the fuels. The analysis is based on manufacturers’ data on new models of fuel consumption (Motor Presse Stuttgart, 2008). While the diesel car fleet shows an average improvement
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Fig. 7. Development of registration weighted car weight of diesels and gasoline cars, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 8. Development of fuel efficiency of the Austrian car fleet by registration weighted fuel consumption, 60 percentiles of car stock 1990–2007, WIFO database.
in fuel efficiency of 1.03% per year, the gasoline car fleet is gaining efficiency improvements by 1.56% on average per year. This amounts to a reduction in fuel consumption per 100 km driven by 16% for diesels and 23.7% for gasoline cars within the observed time period. Registration weighted fuel use was therefore reduced from an average of 7.1 l/100 km to about 6 l/100 km within the diesel fleet and from an average of 9.1 l/100 km to 7 l/100 km within the gasoline fleet. For the total fleet, this results in a reduced diesel-equivalent fuel use of approximately 2 l/100 km within 17 years, resulting in an average annual reduction in fuel use of 1.67% considering the registration weighted car stock. This is a remarkable gain in fuel efficiency taking into account comparable developments from the literature. The OECD and IEA (2001), for example, indicates a gain in fuel efficiency of 1 l of fuel use per 100 km for on-road car stock within 20 years in Germany. The fuel efficiency indicator is translated into grams of CO2 emitted per kilometer driven on the basis of the IPCC standards. Thereafter, in 2007 the average registration weighted car fleet shows 163 g CO2/km for a diesel-equivalent car, 160 g CO2/km for an average diesel car and 165 g CO2/km for an average gasoline car. Fig. 9 shows the development of the average CO2 emissions of the two car fleets as well as a diesel-to-gasoline relationship. The
latter shows a declining efficiency gap between diesel and gasoline cars. One of the implications that can be drawn from this result is that there appears to be a substantial improvement in the average fuel efficiency of registered car stock, despite market shifts towards heavier cars with greater engine size and higher power. Subsequently, we conduct an analysis of the development in fuel efficiency of three different power classes (see Figs. 10 and 11). Within the diesel car stock the highest efficiency gains were realized in the high power car class of 60–80 kW, amounting to an average annual increase in fuel efficiency of 2.4% compared to the middle power class, which showed an increase in efficiency of 1.5%, and the lower class, which lacked efficiency gains at an average annual increase of only 0.3%. Overall, efficiency improvements came to a halt towards the end of the century. What is striking is that smaller power classes show higher average fuel consumption, i.e. the 40–60 kW class shows higher fuel consumption between 1994 and 2003 than the 60–80 kW class, and the lower than 40 kW class shows a higher average fuel consumption than the other two clusters from 1999 onwards. The fact that cars with lower engine power use more fuel can be explained by the practice of curtailing engine power to profit from a lower motor vehicle tax. As motor vehicle tax is calculated on the basis of power classes, there is an intrinsic incentive to reduce
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Fig. 9. Development of average registration weighted CO2 per kilometer, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 10. Development of fuel efficiency of diesel cars clustered by power, 60 percentiles of car stock 1990–2007, WIFO database.
engine power, resulting in significantly higher average fuel consumption. The picture looks slightly different for gasoline car stock (see Fig. 11). Here, fuel efficiency improvements are of the same order of magnitude throughout the three power clusters, ranging from around 1.6% in the lowest class to 1.8% in the highest power class. However, calculations of the fuel efficiency of car fleets based on new car data supplied by manufacturers have been criticized as underestimating the fuel consumption of real-world driving (Schipper and Tax, 1994). This is because test cycles that measure fuel use and CO2 emissions, e.g. the New European Driving Cycle (NEDC) implemented in the EU since January 1996, do not match specific driving profiles, in particular where short distances, urban driving or high-speed motorway driving are the dominant modes of car use. Therefore, assessments of real-world car driving and fuel consumption in relation to test cycle based manufacturer data reveal underestimations in fuel consumption from the test cycles of about 15–25% (Schipper and Tax, 1994). The Austrian Association of Consumer Information has tested several cars, finding a discrepancy between test cycle based and real-world based fuel
consumption of between 3.6% and 29% (Konsument, 2008). The greater discrepancy results from a small size car type (Smart) driven on a motorway test cycle that is not part of the official NEDC. As this car type is not suitable for higher velocities this test of real-world conditions actually significantly drives up CO2 emissions. In general, test cycles used by manufacturers nevertheless provide information on annual improvements in fuel efficiency and are therefore suitable as a comprehensive indicator of technical change. In order to give a representation of the gap between test cycle based measures of fuel efficiency and real-world driving fuel consumption, we have assessed the scope of the gap for the year 2007 using data from the ‘‘spritmonitor’’ web portal.2 The ‘‘spritmonitor’’ portal collects data on fuel consumption clustered into kW power classes from real-world drivers who engage in data collection. As this web portal does not supply time-related data we have limited the assessment to the year 2007. Based on the
2
http://www.spritmonitor.de/de/leistung_kontra_verbrauch.html.
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Fig. 11. Development of fuel efficiency of gasoline cars clustered by power, 60 percentiles of car stock 1990–2007, WIFO database.
Fig. 12. Indicator of (thermodynamic) efficiency: fuel use per kg weight, 60 percentiles of car stock 1990–2007, WIFO database.
data from this year, real-world fuel consumption within registration weighted gasoline car stock is about 1.9% higher than that based on test cycle information. Within diesel registration weighted vehicle stock the discrepancy lies at +5.1% and the diesel-equivalent calculation reveals a real-world fuel consumption which is 3.83% higher than that based on the test cycle. This indicates a smaller range of divergence between actual and theoretical fuel efficiency than the numbers cited above. Presenting another aspect in the fuel efficiency of the Austrian car fleet, an indicator of efficiency in terms of fuel consumption in liters per kg weight of car is presented in Fig. 12. This indicator is known to represent the thermodynamic efficiency of the average car or car stock, i.e. the efficiency of the conversion device. Higher efficiency means that more moving mass is obtained from the same heat content or the same fuel input. Fig. 12 reveals an overall trend towards more efficient cars. In 1990 an average car required 0.008 l of diesel-equivalent fuel to move one kilogram for 100 km. This number has been reduced to 0.005 l per kg in 2007, indicating an increase in thermodynamic efficiency of about 43%. Gasoline-driven
cars improve annually by about 2.35% on registration weighted average while diesel cars show a slightly better annual improvement of 2.56%. When calculating on the basis of diesel-equivalents we obtain a thermodynamic advancement of 3.24% per year. Diesel cars are thermodynamically more efficient than gasoline cars due to the higher heat content of diesel. The shift in the diesel-equivalent efficiency graph towards the diesel line again represents the switch in propulsion systems towards diesel cars. Compared to improvements in fuel consumption per 100 km driven (see Fig. 8), the annual improvement of the thermodynamic efficiency is higher. One of the reasons for the smaller improvement in fuel consumption is that some of the efficiency gains are compensated for by the use of heavier cars. Hence, pure technical efficiency gain has partly been offset by a shift in market demand towards bigger cars. What are the combined influences of the derived fuel efficiencies of the diesel and gasoline fleets, their stock numbers and average vehicle kilometers travelled in terms of CO2 emissions? Using technical registration weighted fuel consumption we calculate the fleet-specific CO2 emissions budgets on the
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Fig. 13. Evolution of CO2emission budgets by diesel and gasoline car fleets, WIFO database, Odyssee database.
basis of data on average vehicle kilometers travelled found in the Odyssee database (see Fig. 13)3. It should be noted that the Odyssee data on average kilometers driven by diesel and gasoline cars constitute model-adjusted data and, thus, may not be considered ‘‘real’’ data in terms of survey-derived data. However, given the fact there are no other data available we calculate the car fleets emissions budgets on the basis of this source. In light of this caveat, the necessity of conducting surveys to elicit the ‘‘real’’ volume of vehicle kilometers travelled by diesel and gasoline cars in order to improve research results shall be emphasized. Comparing the shares of the diesel stock fleet (3) with CO2 emissions shares, we find a gap in terms of higher emissions shares despite the better fuel efficiency of diesel cars. Thus, higher average distances driven by diesel cars over-compensate for improved fuel efficiency. In turn, the gasoline fleet shows an under-proportionate emissions share with regard to its stock fleet share and its lesser fuel efficiency. Based on this analysis, we ascertain a travel induced rebound effect for diesel cars due to a lower service price. This trend may well signal the beginning of a continuously declining diesel share in the total vehicle fleet.
cars indicate a continuing trend towards a demand of higher power classes with respect to diesels. Among diesel cars all clusters showed lower registration figures, with the exception of the over 100 kW power class. This cluster rose by 445%, amounting to an annual growth of 23.6%. Given the ongoing preference for higher power classes there is a persistent trend towards the offsetting of technological efficiency gains. With respect to gasoline cars, which showed lower registration except for the 40–60 kW and the 60–80 kW clusters, we find growth of 4% (0.5% p.a.) and 33.6% (3.7% p.a.), respectively, confirming that gasoline cars are still the preferred small size cars. In total, growth in the number of newly registered cars has come to a halt. From 2002 to 2007 the newly registered car fleet grew by 6.3% at an average annual rate of 1.2%. For the entire observation period, we find growth in the newly registered car fleet to be negative at 5.4%. Finally, a trend reversal in the registration of gasoline and diesel cars can be observed, i.e. the share of diesel has diminished, while that of gasoline cars has grown among newly registered cars. This is due to the lower gap in fuel prices and tax incentives for diesels and to the fact that diesels must be equipped with particle filters that are costly and not suitable for short distance driving.
4. Trend of fuel efficiency of newly registered cars Improvements in new car fuel efficiency should gradually translate into improvements in the fuel consumption of the overall vehicle fleet. The speed at which this takes place depends upon the ratio of new registrations to car stock numbers and on the rate of stock turnover. Analyzing trends in the fuel efficiency of newly registered cars is therefore a good indication of the outlook of average car stock fuel efficiency. However, as the scope of the present study was limited with respect to time and budget, we have not been able to collate the data to present a detailed technological profile of newly registered cars as we did for the passenger car stock. However, data on the newly registered car fleet differentiated by diesel and gasoline as well as by power clusters from 1999 to 2007 (as depicted in Fig. 14) could be obtained from Statistics Austria. The figures for newly registered 3
http://www.odyssee-indicators.org.
5. Conclusions Our study reveals that the Austrian registered vehicle fleet demonstrates a substantial improvement in average registration weighted fuel efficiency. Specifically, fuel consumption was reduced by an annual average of 1.67% which is equal to an increase in fuel efficiency of +25% within the observation period of 1990–2007. This denotes a remarkable reduction in fuel intensity which took place despite a delineated market shift towards heavier cars with greater engine size and higher power capacity. These trends in demand were responsible for partially offsetting potential efficiency gains that could have otherwise been achieved through engine technology improvements and dieselisation (vehicle purchase rebound effect). Dieselisation and technical change, in turn, neutralized the effects from the vehicle purchase rebound towards higher fuel-consuming cars. Finally, the efficiency gains of the average car fleet could have been more
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Fig. 14. Development of newly registered cars by fuel use and power 1999–2007, Statistics Austria.
pronounced without the counteracting shifts in demand patterns towards bigger and heavier cars. However, dieselisation brought about a higher average distance driven per car and, thus, finally over-compensated for diesel-based technological efficiency advantages in terms of vehicle fleet CO2 emissions. Policies that strive to reduce passenger car related CO2 emissions therefore need to address both the promotion of a low carbon passenger car fleet and a reduction in average vehicle kilometers travelled by diesels in order to take full advantage of the diesel efficiency advantage. Policies therefore have to set clear incentives towards the purchase of low fossil fuel consuming cars and neutralize financial incentives on diesel fuels. Based on the trend in dieselisation it is evident that the penetration of a new fuel efficiency system, i.e. of diesel cars, was successfully promoted by demand pull and technology push stimuli. Therefore, we recommend that transport policies opt for favorable vehicle and fuel taxation on low carbon passenger vehicles, e.g. highly fuel-efficient diesel and gasoline, electric, hybrids and natural gas cars. Such policies are to be based on the carbon content of distance driven. Austria has carried out an initial reform of its tax levied upon the first registration of passenger cars in July 2008.4 However, the incentives have to be enhanced in order to swiftly promote a decarbonisation of the Austrian vehicle fleet, i.e. the motor vehicle tax must recur to the average fuel consumption and not to the power class of the car. At the same time a technology push strategy should take care of the necessary supply of low carbon energy-efficient passenger vehicles. Given the positive trend in the average fuel efficiency of the Austrian passenger car fleet, together with the rising trend in passenger car related CO2 emissions, it is clear that the ever rising emissions must be due to the increase in vehicle stock and volume of kilometers travelled. Policies that aim to reduce passenger transport related emissions must therefore also
4 The Normverbrauchsabgabe (NoVa) introduced a tax incentive on cars that emit fewer than 120 g CO2/km. These cars receive a maximum bonus of 300 Euro while cars emitting more than 180 g CO2/km have to pay a penalty of 25 Euros for each gramme emitted in excess of 180 g CO2/km (160 g CO2/km as of 1 January 2010). Alternative fuel vehicles attract a bonus of a maximum of 500 Euros.
counteract the reduced service prices of passenger car use due to efficiency gains.
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