I'm filing this photo in the "highly-doubtful" category. Porsche (or any other car company) doesn't drive prototypes around with identifying badges conspicuously displayed. I see plenty of prototypes running the highways of Detroit metro - always in disguise. If this were real, it would be in heavy disguise. Look at the Cayenne spy photos over the past 2 years. It wasn't until just weeks before release that an undisguised version was photographed. And why is the license plate whited out?
-- Curt