The U.S. Department of Transportation proposes an increase in federal fuel-economy rules of 25% by 2015, which represents the first step in a broader effort to raise the corporate average fuel economy standard for passenger cars and light trucks over the next decade.

Auto makers say they are prepared to meet the proposal’s goal.

The DOT says the proposal would increase fuel economy for passenger cars from 27.5 mpg (8.5 L/100 km) today to 35.7 mpg (6.6 L/100 km) by 2015. It would push the target for light trucks from 23.5 mpg (10.0 L/100 km) in 2010 to 28.6 mpg (8.2 L/100 km) in 2015.

“This proposal is historically ambitious, yet achievable,” Transportation Secretary Mary E. Peters announces during an Earth Day address today in Washington. “It will help us all breathe a little easier by reducing tailpipe emissions, cutting fuel consumption and making driving a little more affordable.”

The proposed rule would allow auto makers to earn credits for exceeding CAFE standards. Peters calls the credit an incentive that additionally provides auto makers flexibility to meet the standards without compromising their economic vitality.

The National Highway Traffic Safety Admin. will seek comment on the proposal for six weeks. A final rule is expected by the end of the year.

Auto makers concurred with the proposal through the industry’s primary trade group, the Alliance of Automobile Manufacturers.

“Congress has set an aggressive, single, nationwide standard and auto makers are prepared to meet that challenge,” says Dave McCurdy, president and CEO of the Washington lobbyist. “This proposal represents an important mile marker on the road to at least 35 miles per gallon by 2020.”

President Bush signed the “35 by 2020” target into law late last year. The legislation marked the largest increase in the CAFE standard in its 32-year history.