I'm afraid I lost heart, and took my 08 offroad-grey Cali with lots of shiny bits to an amazing hand-carwash place near Melksham, run by a family of (I think) Poles. It took 15 minutes, cost 8 quid, and the car looks like it came straight out of the showroom. You could sit in the nice warm neighbouring social club and have a cup of tea while watching them work. And my arms don't ache at all!