The fleet-wide average for U.S. automakers' light-duty vehicles has remained fairly consistent since 1997, ranging between 20.6 mpg and 20.9 mpg, the EPA said in its annual report on fuel economy trends.
The reason, says CBS News Correspondent John Hartge, is weight: The average per vehicle is up to 4,000 pounds now, compared to average vehicles of 3200 pounds in the best MPG year. Cars aren't necessarily heavier: We're buying more trucks and SUVs.
Fleet-average fuel economy peaked at 22.1 mpg in 1987, the EPA said.
Those trends could gain increasing importance for consumers if gasoline prices remain high. Prices are expected to go up by another nickel a gallon nationwide by the end of June before returning to current levels before fall, the Energy Department has estimated. It expects pump prices to average about $1.81 a gallon for the three months ending in June.
EPA officials also hybrid-electric vehicles, clean diesel technology and variable displacement engines hold promise for raising the average in the near future.
Light trucks are so popular that they are expected to account for 48 percent of vehicle sales in 2004, compared with sales of cars at 52 percent, EPA said. Manufacturers also are responding to consumer demands for more power and high-tech accessories, the agency said.