This is an excerpt from EERE Network News, a weekly electronic newsletter.
Fuel Economy for New Vehicles Rises for Fourth Straight Year
The average fuel economy of cars and light trucks sold in the United States for Model Year (MY) 2008 is estimated at 20.8 miles per gallon (mpg), an increase of 0.2 mpg over last year's figure, and that estimate is probably low. The U.S. Environmental Protection Agency (EPA) bases its fuel economy estimates on sales projected by the automakers prior to the launch of the model year, and this year the sale of light trucks—pickups, sport utility vehicles, and minivans—has dropped off precipitously, as sales of small cars have boomed. As a result, automakers have sold more fuel-efficient vehicles than they expected, so the average fuel economy will probably end up higher than the EPA's estimated figures.
U.S. fuel economy reached a peak of 22.0 mpg in MY 1987, and then began a 17-year slide as consumers bought an increasing percentage of light trucks and higher horsepower vehicles each year, outweighing the fuel efficiency gains from improved automotive technologies. But after reaching a low point of 19.3 mpg in MY 2004, a combination of more fuel-efficient vehicles and lower market share for light trucks has caused the average fuel economy to increase by 1.5 mpg, an 8% increase. In that time, the market share of light trucks has dropped from 52% to 48%, while the fuel economy of cars and light trucks increased by 1.0 mpg and 1.4 mpg, respectively.
It's important to note that the EPA recently changed its method of determining fuel economy to better reflect "real-world" conditions, such as faster speeds and the use of air conditioning. To account for that change, the EPA phased in gradual adjustments to the old fuel economy values, starting with MY 1986. Without the adjustment, MY 2008 would achieve an estimated 26.0 mpg, slightly higher than the unadjusted figure for MY 1987, which was 25.9 mpg. In the intervening years, average vehicle weight has increased 28% and average horsepower has increased 88%, yet fuel economy has also increased, thanks to the use of hybrid technologies, variable valve timing, cylinder deactivation, gasoline direct injection, turbocharging, and continuously variable transmissions. See the EPA press release and report on fuel economy trends.