Man, my garage is pretty much the same as the outside temperature. The two-car door is probably not well-insulated (if insulated at all), but two walls are part of the interior of the house and the third wall is insulated the same as the house. But there is no heat in the garage, other than the small, 750W heater I have in that "greenhouse" structure. Since the walls and ceiling of this temporary greenhouse is made of 16 mil solar blanket material, it does hold heat in and cold out very well. I would build the temporary greenhouse out on the patio (and could build a larger one) but I would have a problem anchoring it on that concrete pad.
