BMW, Mercedes, Porsche, Audi, VW and Volvo all use and recommend P21S Wheel Cleaners to remove brake dust and road grime from their alloy wheels. This wheel cleaner has the best reputation for wheel safety of any product available. P21S is a non-acid, water-based detergent that safely cleans all painted, clear-coated, polished or anodized wheels. P21S Gel formula is 50% stronger for wheels with excessive brake dust coatings. I recommend the Gel formula for any car that creates excessive brake dust. 500 ml. spray bottle. Imported from Germany. P21S