WASHINGTON – A plan to increase fuel efficiency standards to an average of 35 miles per gallon by 2020 won approval from a Senate panel Tuesday in a vote closely watched by automakers and environmental groups.

The Senate Commerce, Science and Transportation Committee approved the measure, which would raise the nationwide fleet fuel economy average by about 40 percent from current levels of 25 mpg for cars and trucks. The bill, approved on a voice vote, would also increase standards by 4 percent a year from 2020 through 2030.

“This is not a perfect bill, but I think we have reached a stage where most parties would say this is fair,” said Sen. Daniel Inouye, D-Hawaii, the committee chairman.

He said the bill would be considered before the full Senate in June.

This was lawmakers’ first step in demanding more efficient vehicles from automakers amid concerns about global warming and the nation’s dependence on imported oil. Gasoline prices have leapt in recent weeks to a record nationwide average of $3.07 a gallon, or nearly 20 cents higher than two weeks earlier, according to the Lundberg Survey.

“Saturday night my husband and I were in San Francisco and we paused at a gas station and we literally couldn’t believe our eyes – $4.24 a gallon,” said Sen. Barbara Boxer, D-Calif.

Fuel economy standards have made little progress in the past 20 years. Passenger cars are required to meet a fleetwide average of 27.5 miles per gallon while SUVs, pickup trucks and vans must meet a standard of 22.2 mpg.

Sen. Olympia Snowe, R-Maine, a co-sponsor of the bill, applauded the committee’s action. She said “today’s decision by the Commerce Committee paves the way for all Americans to adopt significantly higher fuel efficiency standards. Our fuel economy standards have been dormant for far too long.”

Lawmakers said the bill was a compromise that would likely face a number of changes on the Senate floor. Sen. Ted Stevens of Alaska, the committee’s top Republican, and Trent Lott, R-Miss., said they had concerns about how it might affect trucks and its overall fairness.

Sen. Bill Nelson, D-Fla., meanwhile, said he would aim for a fleet increase of up to 40 mpg by 2020, while Sen. John Kerry, D-Mass., wants to guarantee 31 mpg by 2015 and 35 mpg by 2020.

The committee also approved by voice vote a proposal by Sen. Maria Cantwell, D-Wash., to create federal criminal penalties for price gouging at the fuel pump if the president declares an emergency because of high energy prices.

Republicans opposed the plan, saying it included an arbitrary definition of price gouging. Sen. Jim DeMint, R-S.C., said it “creates a new playground for the lawyers.”

Under the broader bill, large work trucks and tractor trailers would have to meet fuel economy requirements for the first time. But the timeline was unclear because any requirements would first require a federal study.

Other provisions include letting the National Highway Traffic Safety Administration reform passenger car standards to take into account a vehicle’s dimensions and requiring the government to purchase more fuel-efficient fleet vehicles.

The Alliance of Automobile Manufacturers, which includes Detroit’s automakers and Toyota Motor Corp., have said the proposal would be unattainable and threaten jobs. General Motors Corp., Ford Motor Co. and DaimlerChrysler AG’s Chrysler Group have already announced thousands of job cuts in the past two years.

Alan Reuther, the United Auto Workers’ legislative director, wrote Inouye that it would force manufacturers “to close more facilities, destroying tens of thousands of additional jobs and undermining the economic base of communities across this country.”

Environmentalists said they were concerned that the proposal was weaker than one offered by President Bush, which would set a goal of a 4 percent annual increase while expanding use of alternative fuels.

“When you look at all the loopholes in this 35 mpg bill, it kind of looks like Swiss cheese,” said David Friedman of the Union of Concerned Scientists.