The CLR is working... that stuff is really on there pretty hard, though, so it's still taking a long time. And Presidential is right, I'm gonna have to polish after I get it all off. CLR takes off the physical buildup, but the paint is still marked.

 

I use Meguiar's Marine water spot remover on my ski boat. Had a similar problem on my daughters black A4, so last night I tried it and it worked well.

Meguiar’s #47 Hard Water Spot Remover will remove existing hard water spots and minerals with an easy–to-use formula.

 

im with presidential detail on this one. after i clean my car, i dont even bother to sit there and dry it off. i drive it home, wait till most of the water dries (obviously there will be spots) and then use my moms homemade glass cleaner, which is mostly vinegar, to get out the water spots. looks way nicer than if i just dried it at the car wash and if you plan on waxing after, it takes all the dust off period. nothing left but paint and clear coat

 

Vinegar will work. Then wash and wax the area where you applied the vinegar.

 

Ihave hard water and the same thing happened to me used all the chemical and special cleaners didn't work. mixed about a 50/50 mix of white distilled vinegar and water wiped off easily.