I have the same problem having a black truck that attracks heat. I also live were the water is real hard. I have tried lots of things. I do dry my truck off right away(like i didnt know what caused them lol). I talked to a glass place and they gave my some stuff called A-MAZ(water stain remover) . this stuff works my truck has water spot built up over the 23 years i have owned it. It rubbs on with a damp cloth then rubb off ( repete if needed). this stuff works nothin before even touched the water spots. jay
