Yesterday I noticed a sun spot about the size of a quarter on my roof on the passenger side. You know when the paint starts to come off from prolong exposure to the sun, my car is originally black and the sun spot is greyish. It is minor but I know once you get one they spread as it happened to my mother's car.

My question is that is there anyway to prevent them? Like maybe waxing or claybaring your car? Any ideas?

 

too late to prevent it.... if one spot has appeared, the entire roof panel needs to be refinished (painted).

To prevent it: wash as needed, claybar on front bumper, hood, mirrors and fenders is always good to remove dead bugs and road trash stuck on these panels.
Wax the car 2 or 3 times a year, properly applying the wax and wiping off the residue under a shade, cool area, so panels aren't hot when wax is applied.

 

My 96 accord roof was starting to fade to a dull green instead of the nice gloss green everywhere else on the car, when i saw it start to dull i had waxed it and there was a little difference but i had done it several times that month and after those few times i managed to revive the gloss look