WHITE ON WHITE

If I know I'm going to have to have a real nice bright white, then I will always prime with a white primer. Follow that up with the white of your choosing. Then I will wet sand that white and respray any areas that may need it and wet sand again. Then when I'm happy it is super smooth, but now dull from sanding, I will clear coat it a few coats and then wet sand and polish that to a high gloss finish. If you want and nice gloss finish you will have to put in more work wet sanding and polishing than on any other aspect of the build, by far. But, the results of that work are well worth it.

BK

I would say it needs to be painted,I don't deal with car finishes,but when I did my Phantoms,I would paint the bottom with flat white, and overcoat it with clear gloss.Worked for my aircraft,not so sure about a high gloss car finish. There are specific sections of the forum,maybe post in the Cars section or Painting to get less of a General reply.