I have a 3hp 60g that I use for general shop stuff. I have on a few occasions used it to paint car parts with a standard hf hvlp gun and found too small for anything bigger that a hood and a few panels. Auto paint is pretty thin and I can’t imagine it would work with water based stuff. It would work fine for a single small part though. Echoing what has been said before, some of the airless systems are really nice and would be a lot cheaper than investing 5k into an air compressor.