Here's a little car trick you probably didn't know about.  You can actually roll down your windows just using the remote on your keychain.

On a lot of modern cars from all the major brands, if you press the unlock button, release it, then press it again and hold it down, it should roll down your windows.

That's not the most useful trick, but you could use it to roll the windows down and let some of the unbearable heat out BEFORE you have to sit down inside.

Here's a list of all the brands and models that feature the trick.