Unknown Audi mule spied in California

Spy photographers were baffled when they caught this mule undergoing hot-weather testing in Death Valley, CA.

Rumors suggested that the mule is a possible A5 Sportback. Considering the wheelbase on the vehicle seems unchanged, the A6 is 3 inches longer than the A5 coupe. Raise ride height and 20 inch Audi Q7 alloy wheels doesn't sound like an A5 Sportback. Another rumor is that it could be the A7 coupe, but the A7 is nearly production ready, so that is ruled out. With the large rear wheelarches, it is possible that this could be a 2010 A6 prototype because the wheelarch stretches back onto the rear bumper by 4 inches.

What do you think it is?