I can't stand seeing snow piled on a car's roof, knowing that at anytime the snow and ice could blow onto my car and may even crack or dent something. Completely clear the windshield, roof, hood and trunk area of snow, as well as head and tail light surfaces. You'll find more information here . The main reason we warm a car these days is to make occupants comfortable and defrost windows. When it is far below freezing it helps to warm engine oil before getting underway.
Oil needs to circulate freely to properly lubricate a very cold engine.
As a recent transplant from So. I am reluctant to ask a general mechanic because I am a woman, and they ususally tend to suggest repairs that aren't really needed. Typically this includes a test of your vehicle's antifreeze, battery condition, belts, hoses, wiper blades and tires. If you live in an area where snow and ice cover the road for extended periods, you may also want to switch to snow tires for the season. Americans love to travel even with sky high fuel prices.