This video shows how to make the wheel emblems on your Saab blue again. Saab uses a polycarbonate material for the center disk and it tends to oxidize over time.
Normal washing won’t get them clean. In This video, Saab owner used a Lacquer Thinner – Basically it is a mixture of solvents able to dissolve a number of different resins or plastics.
Also, not bad – The Nail Polish Removal cleaned it up perfect.
And here is another similar DIY video in which the Saab owner used some other matter for cleaning – a Headlight Restoration Kit. And, The result is really extraordinary: