Here is your answer.....yes i sprayed the entire underside of my duster with it and it works great, the nice thing is if you need to touch it up it blends in with the old very nicely.. Now for the clincher i bought a gallon of it and had the hood , side stripes and tail stripes done with it and it looks just like the original paint did on my first duster i had. It is well worth the money and you should really like it and your results. Good luck!