A new Bush administration proposal that light trucks gradually improve their average fuel economy by 1.5 miles per gallon is close to standards automakers were already striving to reach, leading environmentalists to criticize the regulations as meaningless.

The plan, announced Thursday by the National Highway Traffic Safety Commission, calls for an increase in fuel efficiency from the current 20.7 miles per gallon to 22.2 mpg by the 2007 model year. Agency officials said it is based on what is possible with available technology, without requiring automakers to sacrifice performance or reduce vehicle weight.

Anything greater may have required automakers to reduce the size of their vehicles, which could put occupants at greater risk in a crash, NHTSA Administrator Jeffrey Runge said.

"We are very interested in doing whatever we can to enhance fuel economy,'' Runge said. "What we don't want to is to cause a safety consequence.''

Environmentalists said the increase is trivial and will not reduce greenhouse gas emissions and foreign oil dependence.

"The president wants to pose as an advocate of energy conservation while he protects the auto industry's interests,'' said Philip E. Clapp, president of the National Environmental Trust.

The fuel efficiency standard for light trucks — a vehicle class that includes sport utility vehicles, pickups and vans — has been set at 20.7 mpg since 1996. Under a proposal to be issued Friday, it would increase to 21 mpg by the 2005 model year, 21.6 by 2006 and 22.2 by 2007.

The car standard is 27.5 mpg and does not change.

The standards do not apply to every vehicle, but the average of all vehicles that each automaker sells.

The light truck proposal is much less stringent than one considered by Congress this year. Sens. John Kerry, D-Mass., and John McCain, R-Ariz., proposed raising the standard for all vehicles to 35 mpg by 2015, but the Senate rejected the idea last spring.

"The administration is merely ratifying less than what industry is already doing on its own without challenge or incentive,'' said Kerry, who is considering running for president. "I think Americans deserve more than another sham White House effort to pretend to act in the interests of energy security.''

The administration's proposal was based on information provided by the three automakers that sell most of the light trucks in the United States. DaimlerChrysler projected its light truck fleet would average 22.2 mpg by 2007, Ford Motor Co. projected a 22 mpg average and General Motors said its fleet would achieve 19.1 mpg to 20.8 mpg.

NHTSA officials examined each of the automaker's confidential product plans and concluded all three could meet a 22.2 mpg standard. GM and DaimlerChrysler said they had not reviewed the government's proposal and could not comment in detail. Officials at Ford and the Alliance of Automobile Manufacturers said it will be a challenge to meet the standard.

"Those numbers are a real stretch for us,'' Ford spokesman Mike Moran said of the predictions given to NHTSA. "We have a lot of work to do technology-wise to reach those numbers, and our fleet average is determined by what the customer purchases.''

NHTSA predicts the new standard would increase vehicle costs by an average of $47, but the consumer would reap a $100 benefit over the vehicle's life, largely from having to buy less gas.

The agency said it would save 2.5 billion gallons of gas over the life of trucks from the 2005-2007 model years, which environmentalists derided as a drop in the bucket.

"If you measure the fuel savings in gallons you've got a trivial amount,'' said Daniel Lashoff of the Natural Resources Defense Council.

The country uses about 798 million gallons of oil a day, about 40 percent of which is used by motor vehicles. Motor vehicles account for about a fifth of the carbon dioxide emissions linked to climate change.

NHTSA will take public comment on its proposal for two months. A final standard must be issued by April 1, after public comment, to give automakers time to make design changes for the 2005 model year.