Percolation? Heat soak? Don't drive during summer??

Also, the garage might start at 75, but once that door opens it quickly reaches outside temps... Heck, my garage typically didn't even reach the house temp. On a 110-115 degree day (was 118F the day I left the city) my garage was typically 90-95.
That's because you have one of those big fancy yupi 3 car garages.. lol...