I use some bumper stuff that's made by Wonderwheels, called back to black I think. It's a white liquid that you just sponge on, and then buff up in a few minutes. It's magic stuff and lasts ages between washes...only problem is that I haven't seen it on any shelves for sale in quite some time. Halfords used to sell it, but no longer do. If anyone knows where to buy it do let me know, I've only enough left for another year probably!