Yep, it's only the outside. I tried some 3M Scratch Remover (basically machine compound) and it did pretty well without any sanding, but would fail the 3-foot test. If preceeded by some wet sanding, as done by rx7tt95, it would come out quite nice. Since I'm out of Autosol I may finish up the IronMan's lights this way since I've got a few packs of 3M 1500 and 2000. We'll see!