FWIW, I have never done what Airdave talked about. I've done a few glossy car models in my time and I only wetsand to get rid of dust particles that have landed in the paint job. I have no problem getting a clear coat to stick to a gloss paint, but then again I only do cars in lacquer paints. Your result as it is in the photos is fantastic, but aren't there decals? You should want to clear coat to cover the decals.