Automakers would be required to nearly double fleet efficiency to 62 miles per gallon by 2025 under the most ambitious scenario of a U.S. government outlook on fuel economy and emissions released on Friday.

Gasoline and electric hybrid vehicles and electric cars would play a crucial role in meeting the top range targets, according to the preliminary assessment presented to industry as a starting point for developing fuel standards for 2017 cars and light trucks, including SUVs, pickups and vans. Get the full story »