Sorry to be late to this thread. I’d tried everything to clean the beige roof of our 2011 500C. Daft colour of course but it looked lovely when new! Eventually nothing, but nothing could shift the accumulated bird poo residues and tree sap, despite having washed it regularly over the years and used all the recommended products mentioned by others. In the end I had it professionally cleaned and recoloured in a much more sensible black, and re-proofed. I’ve concluded with the blindingly obvious that a car with a fabric roof needs either to be kept in a garage or under a good quality cover - and that the summer months, such as we get, tend to be more troublesome than winter ones. It’s also slightly comforting that dark roofs can end up looking as awful as our once beige one did. Now black it looks pretty smart (Atom Detailing in Sheffield made a very good job of a very challenging refurb - they also repainted the roof ‘spoiler’).