In the archives are some articles that elaborate on the coating that is applied to the rear screen every two years by Audi dealers. However none of the replies identified what the coating is. Although Rain X was mentioned a few times, i understand it is Ombrello. It is retailed in this country by www.weathertec.co.uk. they also supply the trade with trade application packs. For a cheaper method - go to www.weathertec.co.uk/motoring.htm and get a few quid off courtesy of the Telegraph motoring page tie up. Perhaps there could be an opportunity for an A2OC tie up also in view of the A2's need in this dept.