EPA Reports Real-world MPG Stats Trending Upward

By KBB.com Editors on September 22, 2008 1:47 PM

It appears that The Great Gasoline Gouge of 2008 has had at least one positive outcome. A comprehensive new report by the Environmental Protection Agency indicates that the fuel efficiency of the American light-duty vehicle fleet rose from 20.6 mpg in 2007 to 20.8 mpg this year -- and is likely to go slightly beyond that level in the ultimate accounting. The initial data were derived from a comparison of EPA numbers on passenger cars and trucks/SUVs with less than an 8,500-lb Gross Vehicle Weight Rating (GVWR) and based on their relative market shares for 2007 versus this year. The stunning impact rising gasoline prices have had on buyer preferences during the last six months has the EPA believing the de facto rush to smaller and less-thirsty models is virtually certain to generate a further uptick when the actual 12-month figures for 2008 are released. Even in its preliminary state, the government agency says the 20.8 mpg stat represents a 1.5-mpg-or eight percent -- gain over the 19.3 mpg number in 2004, which was the single worst fuel index figure since 1980.

This EPA study, "Light Duty Automotive Technology and Fuel Economy Trends" 1975 Through 2008," also provided some intriguing ancillary data on how the design of vehicles, and particularly advances in their engines, has impacted the automotive scene during that period. While the average curb weight of the fleet in question rose from 4,060 lb to 4,117 lb and horsepower jumped from 137 to 222, the economy numbers moved from 13.1 mpg to the projected 20.8 figure -- and 0-60 mph times dropped from 14.1 seconds to 9.6 ticks. Today, 77 percent of engines have multivalve heads, 58 percent use variable valve timing, 2.3 percent employ direct fuel injection, and seven percent have some sort of cylinder-deactivation system, none of which was found on any 1975-spec engine. The EPA survey also found that eight percent of the current U.S. fleet also is equipped with a continuously variable transmission (CVT), while conventional manual transmission fitment has dropped from 23 percent to only seven percent.