I don't think there's anything chavvy about Audi RSs. No doubt some are driven by undesirables, but I wouldn't say overwhelmingly so at all. If you're going to include them you might as well just say 'any prestigious German car'.
True I should have specified "older". I see quite a few now they are affordable and almost always with black alloys and tinted blacked out windows.
Usually the numberplates are illegal as well, a dead giveaway.
I suppose thats the issue. No matter how good a car was to begin with, a lot end up been driven around by chavs. Some cars like the Saxo are an automatic chav car though.
Some makes/models avoid this though. I have yet to see a chav Aston Martin but I am sure there will be one somewhere.