The other day after reading about the New Mr. Clean Car wash kit on a BMW forum, I decided to go buy it!
As we all know with dark cars, especially black ones you must dry your car immediatley after washing it, or your gonna have hard water stains. So I tried this kit out on my black BMW and long behold I didn't have to dry it and I had no hard water stains. Apperently the filter provided with the nozzle removes all the minerals from the water, so it can be left alone and it will dry without any residue or marks.
I think everyone should try this out, because you will save alot of time drying!