WASHINGTON (Reuters) - Automakers will get significantly more credit for building electric vehicles in meeting U.S. fuel economy rules, than regulators initially proposed, under final rules released Tuesday.

The Energy Department unveiled final rules that significantly soften its proposal to slash electric vehicles' (EV) mileage ratings by 72% in 2027 to meet government fuel economy requirements. The new final rules soften the revisions to the calculations and gradually phase them in through 2030 rather than in 2027.

The decision first reported Monday by Reuters is a win for the Detroit Three automakers and the United Auto Workers union that raised alarm that the proposal could have resulted in U.S. automakers facing $10.5 billion in fines through 2032 for not meeting fuel economy requirements.