Consumer behaviour has partly offset improvements in the efficiency of new vehicles over the past few decades.
Improving the efficiency of new vehicles is often hailed as the most straightforward method for curbing emissions from car use. Technological developments have led to 100% efficiency gains in new cars since the 1990s, but much of the potential savings in emissions and energy have not been realized, a study finds.
Lee Schipper from The University of California, Berkeley analysed records of car efficiency, use and characteristics such as weight and power as well as the real price of fuel from the early 1970s to 2008 in 11 developed countries including Germany, the United Kingdom, Japan and the USA1.
As manufacturers develop more efficient cars, consumers tend to favour larger more powerful cars rather than more economical ones, found Schipper. Combined with average driving distance, this effect explained most of the difference in total fuel consumption between countries, with the US having the heaviest and most powerful cars and Italy having the lightest and least powerful. Much of the efficiency gains between the early 1970s and early 2000s, including those from switching to diesel vehicles, have been offset by this weight, power and distance effect.
References
Schipper, L. Automobile use, fuel economy and CO2 emissions in industrialized countries: Encouraging trends through 2008?. Transport Policy 10.1016/j.tranpol.2010.10.011 (in the press; corrected proof).
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Brown, A. Offsetting efficiency gains. Nature Clim Change (2010). https://doi.org/10.1038/nclimate1023
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DOI: https://doi.org/10.1038/nclimate1023
