You don't need to heat the entire passenger compartment unless folks are in there, though. You just heat the bits that could benefit. This is the same sort of t

You don't need to heat the entire passenger compartment unless folks are in there, though. You just heat the bits that could benefit. This is the same sort of thinking behind the engine block heaters (for combustion engines) folks use when it is cold and a similar theory to trucks that heat their diesel tanks to keep the diesel from turning to gel, though I don't know if that's an issue anymore with modern diesel blends.