As a teenager for a while before becoming shuttle driver and grease monkey, I washed trucks that had made trips to Florida. The front of the trucks were like velvet when they returned. It didn't matter what color they were when they left here, they came back black.
I think the best way to get them off your vechicle is to soak it in gas and thump a match from a safe distance. Then just buy a new car and don't drive it.