I like to keep my garage warm also. I bought a propane warm mornin stove and I set it on the lowest setting at night. It keeps the temp around 40 degrees even in really cold weather, and it doesn't use a lot of gas ( bout 200 gallons per winter) I've got a wood stove to install for next winter, which will sit outside with a heat exchanger on top and a blower fan, should keep er warm as toast.
