91��Ƶ

The Department of Transportation proposed Tuesday to boost fuel-efficiency standards for cars and light trucks by almost 25% by the year 2015.

Transportation Secretary Mary Peters unveiled the proposal, which would boost fuel economy by 4.5% per year, over a five-year period ending in 2015.

“This proposal is historically ambitious, yet achievable,” Peters said in a statement. “It will help us all breathe a little easier by reducing tailpipe emissions, cutting fuel consumption and making driving a little more affordable.”

The proposal did not mention heavy- or medium-duty trucks, but late last year, the Senate approved a measure that would require the National Academy of Sciences to study how best to measure the fuel economy of heavy trucks.

That plan eventually would require the government to create a “fuel efficiency improvement program” for heavy trucks, aimed at achieving “the maximum possible improvement.” (Click here for previous coverage.)

For passenger cars, DOT’s proposal would increase fuel economy to 35.7 miles per gallon, from the current 27.5 mpg. It would boost mileage for light trucks to 28.6 mpg in 2015, from 23.5 mpg in 2010.

The plan would save about 55 billion gallons of fuel and reduce carbon dioxide emissions by about 521 million metric tons, DOT said. It would also allow automakers to earn credits for exceeding corporate average fuel economy, or CAFE, standards.

“Looking at the fuel-efficient technologies already available, it’s easy to see a not-too-distant future when cars fueled by something other than gasoline will be readily available and affordable,” Peters said.

“Until that time, however, we will continue to do what we can, safely and efficiently, to improve gas mileage and help consumers spend less time and less money at the pump.”