Elsevier

Transport Policy

Volume 18, Issue 2, March 2011, Pages 358-372
Transport Policy

Automobile use, fuel economy and CO2 emissions in industrialized countries: Encouraging trends through 2008?

https://doi.org/10.1016/j.tranpol.2010.10.011Get rights and content

Abstract

Car use and fuel economy are factors that determine oil demand and carbon dioxide (CO2) emissions. Recent data on automobile utilization and fuel economy reveal surprising trends that point to changes in oil demand and CO2 emissions. New vehicle and on-road fleet fuel economy have risen in Europe and Japan since the mid 1990s, and in the US since 2003. Combined with a plateau in per capita vehicle use in all countries analyzed, these trends indicate that per capita fuel use and resultant tail-pipe CO2 emissions have stagnated or even declined.

Fuel economy technology, while important, is not the only factor that explains changes in tested and on-road fuel economy, vehicle efficiency and transport emissions across countries. Vehicle size and performance choices by car producers and buyers, and driving distances have also played significant roles in total fuel consumption, and explain most of the differences among countries. Technology applied to new vehicles managed to drive down the fuel use per unit of horsepower or weight by 50%, yet most of the potential fuel savings were negated by overall increased power and weight, particularly in the US. Similarly, the promise of savings from dieselization of the fleet has revealed itself as a minor element of the overall improvement in new vehicle or on-road fuel economy. And the fact that diesels are driven so much more than gasoline cars, a difference that has increased since 1990, argues that those savings are minimal. This latter point is a reminder that car use, not just efficiency or fuel choice, is an important determinant of total fuel use and CO2 emissions.

We speculate that if the upward spiral of car weight and power slows or even reverses (as has been observed in Europe and Japan) and the now mandatory standards in many countries have the intended effect that fuel use will remain flat or only grow weakly for some time. If real fuel prices of 2008, which rivaled their peaks of the early 1980s, fell back somewhat but still remain well above their early 2000 values. If the prices remain high, this, combined with the strengthened fuel economy standards, may finally lead to new patterns of car ownership, use and fuel economy. However, if fuel prices continue their own stagnation or even decline after the peaks of 2008 and car use starts upward, fuel use will increase again, albeit more slowly.

Research Highlights

►Fuel economy of automobile fleets in industrialized countries has been improving since the late 1990s in Europe and since the early part of the 2000s in Japan and the US. Figures tabulated from national authorities reflect real on road consumption and distances driven. ►New vehicle test fuel economy has been improving, but technology has saved fuel faster, permitting ever larger and more powerful cars in the US and, until recently in Japan and Europe. Currently new vehicles in the US use about 24% more fuel/km in real traffic than in tests, those in Europe close to 20%, and those in Japan around 33%. ►The switch to diesel vehicles in Europe has only played a very small role in this improvement, as both diesel and gasoline vehicle fuel economy improved, with that of new gasoline vehicles improving slightly faster than that of new diesels. ►Car use per capita has stagnated in most industrialized countries, a consequence of higher fuel prices and possible other factors, such as road congestion, aging populations, and greater use of air travel.

Section snippets

Automobile fuel use and emissions: a gap in knowledge

Energy use and travel for personal transport in wealthy countries is dominated by automobiles. While fuel economy improvements and some slowing of the rise in ownership and use of automobiles has slowed the growth in fuel use, these vehicles still account for roughly 9% of total energy use (and 20% of oil use) in OECD countries, with higher shares in the United States (IEA, 2004). Their share in total energy use in developing countries is smaller, but rising rapidly (WBCSD, 2004, IEA, 2009).

Data and methods: focusing on the on-road fuel economy of entire fleets

The approach in this work follows the “ASIF” framework, in which fuel use depends on the product of total vehicle travel by vehicle fuel times the fuel intensity of that vehicle travel for each fuel. Adding CO2 emissions requires determining the CO2 content of each fuel used (Schipper et al., 2000). Apelbaum (2009) provides perhaps the most comprehensive review of how information on vehicle stocks, usage, and fuel intensity from both surveys and other sources are assembled to give a good

Results for on-road fuel intensity of the entire fleet

This section focuses on on-road fleet fuel intensity, the quantity directly proportional to energy use and CO2 emissions. Fig. 1 shows on-road fuel intensity of entire light-duty passenger fleets for a wide variety of developed countries from the early 1970s through 2007 or 2008.

Fuel intensity declined rapidly in the US in the 1970s and 1980s, while European countries experienced slower and less dramatic declines. Japan actually experienced an upturn in fuel intensity in the late 1980s and

Fuel economy of each year’s new vehicles

New car fuel economy, as measured by tests and weighted by sales, is an important indicator of how on-road fuel economy will behave as the fleet is renewed. The greater the difference (on road) between the fuel economy of new cars sold and those in the stock, and the more rapidly the stock turns over, the more rapidly the on-road fuel economy of the fleet will change.

A cautionary note: there is no simple way to compare new vehicle fuel intensities from tests among countries, both because test

The race for weight and power

Throughout this report we have avoided using the term “efficiency” for the indicators we have presented. The reason is clear—real fuel efficiency, if expressed as energy required to move a given mass a given distance, or the energy required to provide a given level of power to an engine, or to extract a given amount of power from a given volume has risen markedly in the US and Europe. Based on US and EU data (Environmental Protection Agency (EPA), 2010a, European Commission, 2010), Fig. 4, Fig.

Impact of diesels—disappointing?

Shifting from gasoline to diesel should save fuel and reduce CO2 emissions as well, goes the mantra in Brussels. In technical terms diesels are much more efficient than their gasoline counterparts of similar output (Schipper et al., 2002, Schipper and Fulton., 2009). In matched pairs, the diesel version of an automobile is somewhat heavier than the gasoline version, and has greater power to give roughly the same performance. Yet, because of the intrinsically higher efficiency of a diesel

Driving forces

The foregoing suggests that while improvements in on-road automobile fuel economy are critical for reducing oil demand and GHG emissions, serious oil saving or reduction in GHG emissions – say, bringing automobiles back to their 1990 levels of emissions or fuel use – cannot occur without both reductions in vehicle use and an end to the upward spiral of weight and power as well as improved fuel economy. The data on new vehicle properties and the diesel comparison show that between auto producers

A plateau in vehicle use—the other part of the equation

It was noted that in the “ASIF” approach (Schipper et al., 2000), fuel use or emissions depends on the product of car use (in kilometers/year) and fuel economy or emissions per kilometer. Will car use grow continually with higher incomes? Fig. 10 shows a novel portrayal of vkt/capita over time. The horizontal axis is per capita GDP over time, converted to real 2000 US dollars from real 2000 local currency at purchasing power parity. The vertical axis shows vkt/capita over time for cars. Data

Changing the trends?

Johansson and Schipper’s (1997) and Basso and Oum’s (2007) findings suggest economic forces – fuel prices – are an important determinant of fuel use for cars. In the US, at least, recent work suggests the reaction to higher prices would be small in the short term (Small and van Dender, 2007, Hughes et al., 2008, Hymel et al., 2010). Yet the plateau of vkt/capita or even vkt relative to income in so many countries suggests a larger reaction, particularly as fuel prices have risen slowly but

Conclusions

On-road fuel economy started improving in Japan and Europe by 2000, but hardly at all in the US from the early 1990s until 2003. New-vehicle test fuel economy has improved in all regions in recent years. Improvements in Europe through 2008 fell short of the target expressed in test CO2 emissions but landed about 5% above that figure in 2009. The shift to diesel cars was expected to “spark” significant fuel economy improvements in Europe to meet this target. But for a variety of reasons, new

Acknowledgment

The original version was written at the University of California Transportation Center, where the author was a visiting Scholar. This version of the paper was written with the support of EMBARQ, the WRI Center for Sustainable Transport, and its global strategic partners, the Shell Foundation and the Caterpillar Foundation. The author also acknowledges support of the Precourt Energy Efficiency Center, Stanford University.

Maria Mendiluce of the University of Madrid and Jennifer Carol Place of

References (75)

  • L. Schipper et al.

    Fuel prices and economy: factors effecting land travel

    Transport Policy

    (1993)
  • T. Zachariadis

    On the baseline evolution of automobile fuel economy in Europe

    Energy Policy

    (2006)
  • T. Zachariadis

    The effect of improved safety on fuel economy of European Cars

    Transportation Research Part D: Transport and Environment

    (2008)
  • T. Zachariadis et al.

    Validation of Road Transport Statistics through Energy Efficiency Calculations

    Energy

    (2001)
  • ADEME, (2004–2010). Les Véhicules Particulaires en France. Doneness et References, Paris: ADEME. Accessible for all...
  • F. An et al.

    Passenger Vehicle Greenhouse Gas and Fuel Economy Standards: A Global Update

    (2007)
  • L.J. Basso et al.

    Automobile fuel demand: a critical assessment of empirical methodologies

    Transport Reviews

    (2007)
  • Bipartisan Policy Center

    Performance Driven: New Vision for US Transportation Policy. National Transportation Policy Project

    (2009)
  • D. Bonilla

    Fuel demand on UK roads and dieselisation of fuel economy

    Energy Policy

    (2009)
  • California Air Resources Board (CARB), 2008. Addendum to the Pavley Bill. Available at...
  • Centraal Bureau van Statistiek (CBS), 2010. Survey on automobile use. Accessed September 2010 at...
  • Cerri, V, Hivert, L., 2003. De nouveaux Nouveaux Diésélistes?...
  • Cheah, L., Evans, C., Bandivadekar, A, Heywood, J., 2009. Factor of two: halving the fuel consumption of new US...
  • J. Dargay et al.

    Vehicle ownership and income growth, worldwide: 1960–2030

    Energy Journal

    (2007)
  • S. Davis et al.

    Oak Ridge Transport Energy Data Book (various editions)

    (1980–2010)
  • Deutsches Institute fuer WIrtschaftsforschung (DIW), 2010. Verkehr in Zahlen. (Transport in Figures.) CD rom published...
  • EDMC, 2010 (and previous years). Energy in Japan. Data Handbook (in English). Tokyo: Energy Data and Modeling Center,...
  • EIA

    Annual Energy Outlook for 2009

    (2009)
  • Environmental Protection Agency (EPA), 2010a. Light-duty automotive technology, carbon dioxide emissions, and fuel...
  • EPA, 2010b. EPA and NHTSA finalize historic national program to reduce greenhouse gases and improve fuel economy for...
  • European Commission (EC)

    Towards Fair and Efficient Pricing

    (1996)
  • European Commission (EC), 2010. Monitoring the CO2 emissions from the new passenger cars in the EU: data for the year...
  • L. Fulton

    Saving Oil in Transport: Options and Strategies

    (2000)
  • D.L. Greene

    Cafe or price? An analysis of the effects of federal fuel economy regulations and gasoline price on new car mpg, 1978–89

    The Energy Journal

    (1990)
  • D.L. Greene

    Why CAFE worked

    Energy Policy

    (1998)
  • L. Hivert

    Les Nouveaux Dieselistes

    (1994)
  • Hughes, J., Knittle C., Sperling, D., 2008. Evidence of shift in the short-run Price elasticity of gasoline demand. The...
  • Cited by (0)

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