I had the same problem with my 02 jetta. I spent days with megs 83 and 80 and didnt get much results. I used the 83 with and LC orange which was the most aggressive approach I had and nothing. I even went as far as 3-4 passes with still no results. I may give it one more shot working smaller areas and being more aggressive with the PC. If that doesnt work Ive herd alot about
Menzerna products which are designed for german paint. They cost like $50 a bottle but I herd you get outstanding results.