So I'm leaving my current roofing company because they have some pretty shady business tactics on top of the fact that they are trying to screw my uncle (long story, but it's bad).

I had magnetic signs on my wife's car as well as mine, but upon removing the ones on her car, there's this cloudy.... stuff where the magnet was. Not really much of a residue, but I don't know.

I washed it, still there. I tried spraying brake cleaner on a rag and rubbing it, still there. Any ideas? I'm thinking I'm going to have to buy a buffer, but what compound/product should I use?