Guy I know with a sprint / race a3 has been doing some high speed testing at Silverstone.
His car as stock, (runs hybrid K04, 2wd) got to 146mph down hanger straight.
Then they fitted some "vortex generator" sonic the hedgehog fins on the top of the roof spoiler (it is a nothelle spolier one I think he said).
Test repeated and consistently 3-4mph faster before the braking zone.
removed thenm and back to 146 and 147!
He is looking into whether they are legal for use as some championships do not allow the "silhouette" to change.
So anyone fancy going all sonic for a few mph.....? eeek