It works best, inevitably I suppose, on shallower chips. I did the bonnet this afternoon, which had maybe ten or so chips about the size of small pin heads. Worked just like on the video. Really impressive difference. Anything bigger or deeper just needs more work, which is fine but kind of goes against the quick-fix objective of buying it. I'll give it a coat of wax tomorrow and see what the final result is like. The instruction sheet advises against pressure washing, but I imagine any stone chip repairs are going to be a bit more vulnerable than the rest of the paintwork.