How do you cool down a hot interior?

Have you ever walked across a hot asphalt parking lot, and, with each step, dreaded the moment you have to open the car door and climb into an oven? That hot summer sun: we love it, we hate it. But who enjoys burning their hammies, their hands, and every other body part that makes contact with a car's interior on a hot summer day? The good news is that I am the "Sultan of Cool," bearing tips to he