There looks to be a difference in the wheel arches on the show car to the test mule that wore that front nose. Maybe it's a trick of the light or is this running RS6 style fenders.
Edit:
Just saw your latest post. A rare occasion when I hate being right, clearly the fender thing was indeed a trick of the light. It just didn't seem logical to show the RS5 this early before it's official production release and before the TT/RS which is to be the next production model to come from Quattro GmbH.
I take it there is no word on the Concept that everyone was talking about?