We all like to be comfortable. No one walks around saying, "I can't wait to sit in my horrible cactus chair." It just never happens. One of the most uncomfortable things to deal with is the cold. It's cold in our garages, therefore, we might heat the garage to eliminate our discomfort. Not so fast, Cold-o. Here are two good reasons to not heat your garage.
Unless your garage is doing more than just storing your car, heating it is not a judicious use of energy. Avoiding a few moments of cold, isn't worth the energy expenditure. Especially since...
A heated garage is bad for your car. It decreases the car's overall lifespan. If you're heating your garage to prolong your car battery, you'd be better off wasting a battery and hanging onto a car.
From the Car Talk Guys on Cars.com:
Heat accelerates oxidation, also known as rust. You drive in the garage with snow and ice on your car, it melts, and the water and salt mix in that nice, warm petri dish and, come morning, there's less of your car there.