WASHINGTON — President Barack Obama and automobile manufacturers today announced a deal that will save drivers money at the pump and dramatically cut heat-trapping gases coming from tailpipes.

The agreement pledges to double overall fuel economy to 54.5 miles per gallon by 2025, bringing major under-the-hood changes for the nation’s automobiles starting in model year 2017. Cars and trucks on the road today average 27 miles per gallon.

“This agreement on fuel standards represents the single most important step we have taken as a nation to reduce our dependence on foreign oil,” Obama said, sharing the stage with top executives of the major automakers before a backdrop of some of the most cutting-edge cars on the road.

For American families, the president said the agreement — which will be subject to a mid-course review — means filling up the car every two weeks, instead of every week. That would save $8,000 in fuel costs over the life of a vehicle, he said.