Rhino Goo (revisited)
A member asked me to report on the above product on another thread, On returning home on Friday after a 270 mile round trip in bad weather I washed the van yesterday, I used this product on the rear of the van to test it, I sprayed it on waited 5 minutes
and hosed it off no sponge or brush,excellent, it got rid of the black streaks as well, I then sprayed it on the roof (which had not been cleaned since arriving back from Spain in October and was really dirty,it got most of the dirt off but I did use a brush
to get the stubborn dirt off, which was not very much. In summary, I was very pleased with the result, the van is now sparkling. I bought it online via Amazon (RNLI) and cost £7.49 delivered for one litre, I then used it to clean both our cars with great results,
no sponge or brushing required. It was so easy to use and economical to use, and no I have no connections with this product so can recommend it, and will be ordering a 5 litre container for future use. 
Admiral