WASHINGTON -- The Obama administration introduced rules Tuesday to double fuel economy for cars and light-duty trucks by 2025, a move that it says will be comparable to cutting a dollar a gallon from the price of gasoline and that auto dealers warned would raise the cost of a new car.The rules boost fuel economy to the equivalent of 54.5 miles per gallon over the next 13 years, building on the White House's effort to raise fuel economy to 35.5 mpg by 2016. The rules are aimed at prodding manufacturers to make more fuel-efficient cars and at dramatically curbing greenhouse gas emissions."These fuel standards represent the single most important step we've ever taken to reduce our dependence on foreign oil," President Barack Obama said in a statement. Last year, 13 major automakers and the United Auto Workers announced support for the new standards, which average across a carmaker's entire fleet. The rules don't mean that cars and trucks will average 54.5 mpg. It's actually closer to 40 mpg in real-world driving.Under the complex regulations, dubbed Corporate Average Fuel Economy, automakers can have lower mileage by using credits for selling electric and natural gas vehicles, changing air-conditioning fluid to one that pollutes less, and placing louvers on car grilles to improve aerodynamics. They won't have to improve pickup mileage much for the first few years, but big improvements will come after 2020.Republican presidential candidate Mitt Romney has said he opposes the standards. Having manufacturers meet them by building cars that consumers don't want is the wrong approach, Romney said.But the Obama administration said the rules give regulatory certainty to the nation's hard-hit automakers. When combined with previous standards, the administration said, the new rules will nearly double the fuel efficiency of new vehicles in 2025."We're raising the bar and making sure that Americans are preparing for fluctuations in gas prices," Transportation Secretary Ray LaHood said Tuesday.The Union of Concerned Scientists estimates that the standards could cut oil use by as much as 3.1 million barrels per day by 2030 -- roughly the amount the U.S. imports from the Persian Gulf and Venezuela combined."Twenty years from now, we'll be looking back on this as the day we chose innovation over stagnation," said Michelle Robinson, director of the group's clean-vehicles program.New-car dealers support continuous fuel economy increases, said Bill Underriner, chairman of the National Automobile Dealers Association.But they remain concerned that the new rules, coupled with the administration's previous regulations, will raise the average price of a new vehicle by as much as $3,000.This report includes material from The Associated Press.