Regulators estimate the new rule will result in an average of 34.9 miles per gallon by model year 2031, down from an earlier projection of 50.4 mpg.

NEW YORK — The Trump administration on Monday plans to release new fuel economy standards that would relax regulatory requirements for U.S. automakers to control pollution from gasoline-powered cars a...

Last December, the National Highway Traffic Safety Administration projected that the new standards would set the industry fleetwide average for light-duty vehicles at roughly 34.5 miles per gallon in ...