Money Should I start my car and let it warm up in cold weather? Experts explain the best way to do it. January 14, 2022Coral Murphy Marcos, Dalvin Brown and Ben Tobin, USA TODAYComments Off on Should I start my car and let it warm up in cold weather? Experts explain the best way to do it. Letting a car idle requires more time for the vehicle to warm up and allows excess fuel to get into the engine, which isn't good for wear and tear.