While I've done a number of vehicles for myself and customers in various forms/finishes, I am partial to the fully painted undercarriage, it looks much more professional, the "factory" oversprayed primer undercarriage while correct for an OEM build just looks like a hack job on a modified/customized car,...for an undercoated car, i much prefer using products like Rustoleums Bedliner in the sprayable gallon formula, it looks like "factory" when applied properly, yet doesn't discolor or absorb greases/oils like the factory stuff did....

Mike