My smart roadster has the same problem,the back wheels look like brand new and the fronts look dirty and old, after 4 years the finish started to bubble through on the fronts, so I had all 4 wheels powdercoated black, it looks brilliant, it looks cleaner for longer and it cleans easier with a soft sponge instead of a bristly brush.
I know you still have the brake dust problems, even changing the pads does'nt help, but it makes the car look better, which is what you are after at the end of the day.

Ellis