Hello, My 2004 SE Tourer 2.0 Petrol is solid black, and as expected it not only is a pain to keep clean, it is also a pleasure to see when it is properly clean. This time I'm planning to get that black properly back to black as detailed below but... Your opinion and experience counts, feel welcome to comment: Turtle Black Box Ultimate Naviwax Carnauba or alternatively Naviwax Ioncoat for Dark Colours. I have heard PTFE products provide really hard shell protection for long periods of time, but I never tried them. At least Carnauba is time tested, though I am not sure if Naviwax is guaranteed high Carnauba content. Users apparently swear by it.