When I bought my car, I got this fairly expensive Porsche cleaner and top treatment (2 separate bottles). The cleaner seemed to work very well, and the treatment is supposed to be like a super-scotchgard that is UV-resistant. 1.5 years later, the top still beads water and it is very easy to clean. Caution: the treatment requires extensive masking of painted areas/glass on the car. the coating is a notorious PITA to remove.