My car had some pretty bad water spots all over it when I bought it. I used CG's product to clean it up. It was a bit of work to really get them off, but they did come off. I've been really careful to not park near sprinklers since then, and have only had to use it again once. That was right after getting some spots and they came right off that time.
https://www.chemicalguys.com/product...r-spot-remover