The Trump administration is backing away from a plan to freeze tailpipe-emissions targets for new vehicles through 2025, say people familiar with the process.

The administration is now considering requiring a 1.5% annual increase in fleetwide fuel efficiency, using an industry measure that takes both gas mileage and emissions reductions into account, the people said. That number is closer to the Obama-era rules calling for 5% gains but still provides auto makers with significant relief and would allow cars to emit more pollution.