Does anybody have any advice on soundproofing a car? I'm figuring that most of the sound comes in through the doors and the wheel wells, but that is just a guess. If anybody has any suggestions on what materials to use and where to put them, that would be great.

The other thing I have thought about would be to use the stuff they use to coat the beds of pick-up trucks. Would this stuff work? I know it would be easy to apply to all of the spots on my trunk. Or how about asphalt roofing materials? Would dynamat be the only way to go?

-Thanks