This was a common topic at the Ann. meet...
Randy (el Presidente), had some stuff called Novus. It was a three step process that worked with pretty good success.
Sunday night before the plant tour, someone had some plastic polish made by Eagle One. I looked at Pep Boys last week and they did not have it. It was a paste, and seemed to work well. It made the rounds from car to car....I'm sorry I can't remember whose it was, but he was generous with it!