Auto makers and car dealers, emboldened by rising profits and a more business-friendly Congress, say they will fight the Obama administration's proposal to boost average new-car fuel economy to as much as 62 miles a gallon by 2025.

The auto makers' main trade group accused regulators in documents filed last week of understating the costs by billions of dollars and suggested the industry might go to court over the issue.

It's a fresh sign that the "go along to get along" approach some industries took during the first two years of the Obama administration is over.

Dave McCurdy, president of the Alliance of Automobile Manufacturers, the industry's main trade group, said he expects the new Republican-controlled House to review "regulations and policies that they would deem harmful to the overall business environment." He noted that the auto industry is the only sector currently regulated for carbon-dioxide emissions.

Less than two years ago, the heads of the Detroit Three auto makers— General Motors, Chrysler Group and Ford Motor— pleaded before Congress for immediate government aid to prevent an industry collapse. Months later, in the middle of the government's bailout efforts for GM and Chrysler, industry executives signed a deal with the White House and California agreeing to boost fuel-economy standards nearly 35% by 2016 in return for California's agreement not to develop its own, separate fuel-economy rules.

But in recent months the industry has steered back toward a more confrontational posture. Auto makers lobbied heavily against a bill to mandate new safety technologies and increased government oversight, which was proposed in response to the uproar over Toyota Motor Corp.'s sudden acceleration recalls. That legislation now appears all but dead.