Regular body filler like evercoat's rage should not be applied over paint.
For your app of smoothing minor dings and scratches the best product to use is a poly glaze product. Evercoat's metal glaze or Upol's dolphin glaze.
A poly glaze product is different from regular fillers is that the filler material(talc) is ground up finer. They are a thinner product that is designed to be applied over sanded paint to fill minor surface imperfections


Currently working on custom metal and How to videos.

1949 and 1972 chevy trucks
70 chevelle SS455
Pictures of my work and projects
http://community.webshots.com/user/sevt_chevelle