Never done it but i leave mine in the car with the windows up and car running. Remote start baby.. Crank up the AC, lock the door and by the time i get back in, i have to turn the AC down some b/c its almost too cold in there. Major isn't panting in the least when i return. Ive almost broken a car window before for a dog, but as i was contemplating it, the owner came back to the car and left. No idea how long the dog was in there. Couldve been 3 min, couldve been 30.