Here's the trick:
when your car is hot from being in the sun you can cool it down by rolling down one window and then,
on the opposite side, open and close the car door around a half-dozen times.
It pumps cooler air in from outside the car like a big set of bellows.
You won't believe how fast it cools the car down.
(of course you need to have cooler air outside your car to pump in - not a given).
