Fuel efficiency of U.S. cars and light trucks will nearly double by 2025 under a standard finalized by the Obama Administration on Tuesday.

American vehicles will get 54.5 miles to the gallon in the new standard that aims to save consumers at the fuel pump and cut dependency on foreign oil imports.

The rule, strongly opposed by Republicans and some car makers, builds on the standard for vehicles for model years 2011-2016, which requires automakers to raise average fuel efficiency to 35.5 mpg.

The new standard is the result of over a year of negotiations among the administration, automakers and environmental groups.

"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.

The new fuel efficiency standards will save consumers $1.7 trillion in gasoline costs and reduce U.S. oil consumption by 12 billion barrels over the period, according to the White House.

Obama initially proposed the standard last July, with the support of automakers, including Ford Motor Co, General Motors Co, Chrysler, BMW, Honda Motor Co Ltd, as well as the United Auto Workers union.

The standard is based on one set by California, which played an "integral" role in developing the national program, according to the White House.

Republicans on the House Oversight and Government Reform Committee has been critical of the administration's tactics in developing the rule and of California's role in shaping the standards.

They released a report earlier this month which said the fuel economy standards were based on an "overly optimistic" view that Americans were willing to buy hybrid or electric cars.

The Obama administration has made fuel efficiency a signature environmental and energy priority since cars and trucks account for 20 percent of carbon emissions and more than 40 percent of U.S. oil consumption.