a section about 6 inches wide. Is this rust starting underneath? It's a 2004 Toyota Corolla. I think it may need to be stripped down to the bare metal. Has anyone had this? It's the original factory (black) paint.
It sounds like rust, which is a little surprising given the age. Good luck.
you are correct, its rust starting underneath, and it would need sanded down to bare metal where the rust is, then primed in that area, if its the roof then the whole roof needs repainted. theres no way to only paint a small area and make it look good. its a cheap fix, probably 250-400 bucks. which when it comes to body work, is cheap