The average fuel economy has risen dramatically since the Arab oil embargo began in October 1973, the Energy Information Administration, analytical arm of the Energy Department, said in its latest annual outlook.
"New-vehicle fuel economy has more than doubled since the 1970s. Moreover, new-vehicle fuel economy is projected to continue to increase by more than 50 percent by 2040," the EIA said in a briefing Thursday.
The U.S. government last year called for a fuel economy of 54.5 miles per gallon by 2025. Last month, the Energy Department said it was backing 38 different projects to improve fuel efficiency, lower transportation costs and cut down on greenhouse gas emissions.
The University of Michigan said the average "window sticker" rating for fuel economy of vehicles in July was 24.8 miles per gallon.