I was asked this question the other day regarding work I used to do on commerical trucks and tractor trucks; we would always( on all over paint jobs at least paint the chassis, just to make the job look better, we used a cheap acrylic enamel, but thinned it with laquer thinner and used a fast 2k hardener. It wasnt super shiny, but dried really fast and the hardener gave ti some durability. It's a cheap and easy fix for a car that getsd driven a lot...tho you're probly looking for a better looking or more durable fix I thought it was worth sharing in case anyone could use it!