My BMW 650i's soft top went green and when I got the green stuff off it left round spots of lichen, and nothing seems to shift it! It was less than a year ago that I did the full restoration with Renovo: cleaner, recolouring and Ultraproofer.

So, I'm going to try all sorts of stuff to try and get the lichen off car shampoo, washing up liquid (dish soap) and a mild bleach called Milton tablets. Let's see how well that goes!