Vinyl Cleaning

[tiger 6]

I have one of Peter Brock`s Superformance Cobra Daytona`s. On the rear of the car is a white half cove with the number 9 in black. The half cove material is made of vinyl. Over the past year or so, the material has become "stained" from the exhaust coming from under the rear of the car. Despite cleaning this area often with everything from Klasse AIO, Griot`s No. 2 polish etc, I have not been able to get all the discoloration out. Any ideas as to what could be used on a vinyl material to clean it up?

Thanks.

[SVR]

Poorboys SSR 1 works nicely on really badly stained vinyls