Something to think about on this topic: 70-80% of the energy used to move your 2 ton block of metals, composites, and flesh is lost to heat (depending on engine efficiency and other factors like regenerative breaking). There are of course other factors like large commercial AC systems that converge above the garage and other openings for air flow, but it takes a hell of a lot of energy to move a car and any heat not sucked away by the air moving through the intake is dumped into the garage. On a hot day, any cooling systems in the car are also prone to be less effective so you're "carrying" more heat into the garage than you would on a normal day.