I have the old Maltese cross wheels on my Z and they were looking REALLLY bad. All of the clearcoat had turned yellow, and the paint was flaking off. They were also covered in layers of roadgrime and brakedust. The nasty looking wheels were really bugging me so I tried to spiff them up (I figured that I had nothing to lose, since they were already really nasty).

I ended up using some paint stripping gel from Sears on them coupled with the blasting from a pressure sprayer (1650 psi). MY GOD, that made a world of difference! They almost look new now, aside from some pits and dings in the aluminum. It was really easy, and only took me a couple of hours of repeated snotting and blasting. By far, this was the cheapest and easiest "exterior modification" that I have performed.

 

I have heard of a lot of people who take off the clear coat with a paint stripper and it seems to brighten them up a lot. I plan on doing something like this to my wheels, they are looking kind of bad.