I just bought a used 2005 Z4 roadster. It was in great condition except for a few dark marks on the light colored top. I have tried a product called "Convertible Top Cleaner" by Bluemagic without success. On one spot, I used xylene - it lightened the stain quite a bit but the stain is still visible. I'm concerned that the solvent may damage the fabric if used too aggressively. Any ideas?
