The Trump administration wants to freeze fuel-efficiency standards for cars and light trucks at 37 mpg, a move that would reverse an Obama-era policy calling on automakers to hit an efficiency target of 54.5 mpg by 2025 . The proposal also would prohibit states such as California from setting their own emissions standards. Automakers support the potential change, citing the difficulty of building to different emissions specifications and the high cost of developing more fuel-efficient vehicles. But environmental and consumer advocates contend better fuel efficiency is needed to slow climate change. They also dismiss the U.S. Department of Transportation’s logic that holding the line on fuel efficiency could save lives and improve safety on the roads. The agency said lowering the cost of new vehicles would encourage Americans to trade in their older cars for newer rides that have up-to-date safety technology.…