I disagree with who said that street racing are not the best comparison test. I think that this is the only test (safety conditions allowing). Tracks are very different from the real world, and even those “Jurassic Monstrous engines American Seventies” (with all my respects but their not for my personal taste) do great quarter mile times.
I think that a lot of things could have happen. The RS4 was with their Y-pipe disconnected (a very usual problem), turbo problems, bad fuel, dement driver, etc.
But, definitely the RS4 loose.
The only thing that I can reinforce for the MB guys is: Save this video in a carefully manner, cause it is unique.
Try this:
http://www.rs4-imola.com.br/downloads.htm