The National Highway Traffic Safety Administration said the rule change originally proposed in December would save 3.6 billion gallons of gasoline over the lifetime of the vehicles affected.
"This increase represents the first increase since (model year) 1996 and is the greatest increase in fuel economy standards in the last 20 years," said NHTSA Administrator Jeffrey Runge.
Light trucks currently are required to meet a corporate average fuel economy of 20.7 miles per gallon. That will increase to 21 miles per gallon for 2005 models, 21.6 mpg for 2006 and 22.2 miles per gallon for 2007 models -- the first change since fuel economy standards were frozen by Congress for six years in 1996.
Passenger cars are required to average 27.7 miles per gallon.
Automakers said it will require new technology for them to meet the new mileage standards because of consumers' buying preferences for larger vehicles. More than half the vehicles sold in the United States since 2001 have been minivans, pickups and sport-utility vehicles, all considered light trucks.
Consumer groups and conservationists said the increases in the final rule published by NHTSA Tuesday squandered a golden opportunity to reduce dependence on foreign oil.
"The agency's rule making on this matter is a sham," said Joan Claybrook, a former NHTSA administrator 1977-81 who heads the group Public Citizen. "NHTSA failed to budge from its proposal last fall, deciding instead to ratify numbers it had already set, despite receiving tens of thousands of comments from citizens calling for a tougher standard."
President George W. Bush in his State of the Union speech proposed tax incentives to get Americans to buy more fuel-efficient vehicles and proposed $1.2 billion in funding for research on hydrogen fuel cell-powered vehicles.