Washington, D.C. ? The government today plans to release a proposal to raise fuel efficiency standards for new cars and trucks, putting the nation’s fleet on track to reach 35 miles per gallon by 2020.

Transportation Department Secretary Mary Peters was making the Earth Day announcement in Washington, responding to a new energy law pushed by Congress last year and signed by President Bush.

Congress sought tougher standards requiring the nation’s fleet of new vehicles to increase its efficiency by 10 mpg from its current average of 25 mpg, or a 40 percent increase. The new law represented the first major changes to the auto mileage rules in three decades.

The proposal will set fuel economy standards from 2011 to 2015 and is expected to be finalized before the end of the Bush administration.

The fleet of new passenger cars is currently required to meet a 27.5 mpg average, while sport utility vehicles, pickup trucks and vans need to hit a target of 22.5 mpg.