Corporate Average Fuel Economy Standards

May 7, 2012, 6:16 pm
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Higher vehicle fuel efficiencies would conserve limited natural resources, reduce dependence on unreliable sources of petroleum, improve the balance of trade for many countries, and mitigate air pollution and greenhouse gas emissions. Most people agree with these goals, yet economic market forces such as taxes on fuel and vehicles have proved insufficient to achieve them. [1] Consequently, governments have pressured automobile manufacturers to improve the fuel efficiency of their light-duty vehicles.

In the aftermath of the 1973 oil embargo, the U.S. Congress enacted the Corporate Average Fuel Economy (CAFE) regulations. These regulations established the average fuel economy of passenger cars in a manufacturer's U.S. fleet at 18 mpg (7.7 km L–1 or km/L) in 1978 and 27.5 mpg (11.7 km L–1) in 1985 and of small trucks at 17.2 mpg (7.3 km L–1) in 1979 and 21.6 mpg (9.2 km L–1) in 1985. These regulations have been controversial from their inception and have generated sharp disagreements about their effects and effectiveness. [2]

To begin with, the CAFE regulations have several loopholes. One, which proved large enough to drive a truck through, is that sport utility vehicles (SUVs), light-duty pickup trucks, and vans fall under the more lax standards of small trucks and thus require less costly technology for compliance. With their lower prices and their desirable larger sizes, the public purchased more and more of these vehicles as passenger vehicles. The market share of SUVs, small trucks, and vans in the United States grew from less than 20% of new vehicles sold in 1975 to nearly 50% of new vehicles sold today.

Another loophole is that, in the calculation of the fleet fuel-economy averages for a manufacturer, CAFE regulations hold alternative-fuel or dual-fuel vehicles to a standard different from that for other vehicles. Fuel efficiencies of dual-fuel vehicles are multiplied by their percentage of alternative fuel use times 6.67. For instance, a 15-mpg vehicle supposedly dedicated exclusively to alternative fuels would rate as if it were a 100-mpg vehicle (15 × 100% × 6.67). In reality, most dual-fuel vehicles in the United States never burn anything but gasoline, and most owners of a duel-fuel vehicle do not even know that they are driving one. [3] Thus, this loophole inflates fleet fuel-economy averages.

That said, the CAFE regulations did spur the development of more fuel-efficient technologies, and automobile manufacturers have adopted many of them. Fuel efficiencies of cars and small trucks at a given weight improved about 70% between 1975 and 2006. Indeed, vehicles in the United States would be much more fuel efficient today if they were the same size as yesteryear, but vehicle weight and engine power increased 30% and 115%, respectively, from 1981 to 2006. As a result, fuel efficiencies of both new and all vehicles in the United States have remained stagnant for over a decade.

The CAFE standards have also affected the safety of vehicles on the road. The SUVs and pickup trucks that have become increasingly popular since the 1970s have higher fatality rates than cars and vans of equivalent weights. Pickup trucks and SUVs attach a body shell to a rigid chassis, and the shell tends to collapse upon the occupants during a collision, whereas passenger cars integrate the body shell with a flexible chassis to provide better protection for the occupants. In addition, SUVs have high centers of gravity and short wheelbases that are, in some cases, more prone to rollovers.

Not surprisingly, as CAFE regulations have changed the makeup of vehicles on the road, they have also affected the cost of producing and purchasing consumer automobiles. In improving fuel efficiencies, manufacturers can focus either extracting more energy out of the fuel combusted or diminishing the effort required to propel the vehicle. Additional costs for these technological improvements range from negligible for simple body aerodynamics to many thousands of dollars for gasoline-electric hybrid systems.

The prospect of rising costs as a consequence of climate change mitigation strategies has fueled further debate about the both the CAFE standards and the health of the auto industry. The CAFE fuel efficiency regulations have resisted major revisions over the years. The state of California passed legislation in 2006 requiring higher vehicle fuel but these are being contested in the courts. In 2007, the U.S. Congress seemed poised to raise the standards gradually to about 35 mpg (14.9 km L–1) for passenger cars as well as set higher standards for SUVs and small trucks based on weight or volume, but as of June 2009, passage of these provisions was still under debate.

Many other countries also have standards for vehicle fuel efficiencies, and quite a few of them will soon exceed 15 km L–1 (35.3 mpg).

[1] National Research Council (2002) Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards, National Academy of Sciences, Washington, D.C., http://books.nap.edu/execsumm_pdf/10172.pdf.

[2] National Research Council (2002) Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards, National Academy of Sciences, Washington, D.C., http://books.nap.edu/execsumm_pdf/10172.pdf.

[3] Energy Efficiency and Renewable Energy (2009) Alternative and Advanced Vehicles. U.S. Department of Energy, http://www.afdc.energy.gov/afdc/vehicles/flexible_fuel.html, accessed January 18, 2009.

This is an excerpt from the book Global Climate Change: Convergence of Disciplines by Dr. Arnold J. Bloom and taken from UCVerse of the University of California.

©2010 Sinauer Associates and UC Regents



Bloom, A. (2012). Corporate Average Fuel Economy Standards. Retrieved from http://www.eoearth.org/view/article/51cbf00a7896bb431f69fff0


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