What color is the paint you are trying to buff out? If it's a light color, you can try washing the whole car with a terry cloth rag and some Comet in the green can. It clearly states it will not scratch delicate surfaces. It's much different than a course scouring powder like Bon Ami.
I've washed dozens of faded light colored cars with the stuff over the past 40+ years, and people are in disbelief that I didn't spend hours machine polishing the cars when they see them.
Work in the shade doing small sections using circular patterns and rinse well as you go. For the disbeliever's, try a small section down low on a light colored car, before you knock it.
