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Efficiency

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Corporate Average Fuel Economy Standards Last Updated on 2010-11-12 00:00:00 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... More »
Driving Conditions, Behaviors, and Traffic Last Updated on 2010-11-12 00:00:00 Average fuel efficiencies of light-duty vehicles vary by 60% among industrialized countries. During the past 15 years, efficiencies have improved steadily in Western Europe but have remained relatively unchanged in Japan, Australia, and the United States. Driving conditions and behaviors exert a major influence on average fuel efficiency. Newer vehicles have better aerodynamics and thus are more efficient at higher speeds than older vehicles. Nonetheless, due to wind resistance, (which is proportional to the square of a vehicle’s speed) vehicles moving at 75 mph (121 kmph) are still 20% less efficient than those moving at 55 mph (89 kmph). After the 1973 oil crisis, the U.S. Congress capped the speed limit on all roads at 55 mph to promote higher fuel efficiencies. This restriction was so unpopular that Congress raised the limit to 65 mph in 1987 and repealed the law... More »