Originally Posted by Fabrik8

A rubbing compound is the same type of product as a buffing compound, both being an abrasive paste. I should have said buffing compound, because they leave a finer surface finish, but I use the two terms interchangeably.

Anyway, if its just dirt and grime trapped in the paint, try a mild paint polish/cleaner system like McGuiars (which I can't spell). The system is a cleaner, a polish, and a wax, and it's designed for just what you need. It's also completely chemical, with no abrasives.
If that doesn't work, try a finishing/buffing compound, which is a very mild abrasive and usually just enough to remove surface swirl marks and grime. If you're shopping, make sure you buy something that can be used by hand (not a machine). Then follow with a polish and wax.

Whatever you do, it wouldn't hurt to do the rest of the car while you're at it....