Yeah, my wife drives a Jeep Liberty Limited with the same. I'm actually thinking about some sort of heater for the whole of the garage. Keep the inside temps well up above the winter outside. Frontgate has something from Delonghi marked down to $75 from the normal list of $250.
http://www.frontgate.com/fg/pdp.jsp?Showarrow=y&prod_oid=3836551&Category_key=-13675&k=XX23159
I just don't know how I feel about a propane driven space heater running 24/7 in a garage with 2 vehicles, the lawn mower, propane and gas tanks, paint cans, etc.