try the Mr. Clean Magic Eraser. had about 2-3 months of brake dust caked on my factory alloys and Mr. Clean took care of business w/ minimal effort.
spray your wheels with some water, then wet the "sponge" followed by wringing it out (mainly just getting the sponge damp, but you dont want it...
i started in a new JCW tuned Mini Cooper S back in 06; definitely one of my favorite cars i've ever driven. had plenty of power for such a small car, however i needed more space since 2 pieces of luggage would fill up the trunk.
so.....traded the Mini back to the dealership for BMW 330ci ZHP...
Turbosmart BOV, HKS Intake, Cobb FMIC, Cobb Downpipe, Greddy Ti-C exhaust
Undecided about the wheels: prefer volk CE28N wheels but you can throw down some serious cash. probably get a set of rota's or powder coat some RX-8's bronze