by Steven J. Ewing (RSS feed) on Feb 7th 2011 at 3:31PM Normally, any spy shots having to do with Audi's RS series involve large wheels, huge fender flares and low-profile tires. This potential prototype for the Audi RS7 Sportback, however, appears to be going incognito under standard A7 skin. The dead giveaway that this A7 is more than meets the eye? The brakes. Specifically, our spy photographers tell us that they've seen prototypes of the standard S7 Sportback plenty of times, and none of those cars we fitted with brakes this large. Even so, the quad exhaust pipes out back are similar to what all of Audi's S models use, though we're told that when it hits production, the RS7 will use a large, dual-exhaust setup. As for what's underhood, the latest speculation suggests that a twin-turbocharged 4.0-liter V8 engine will be in use, producing somewhere around 550 or 600 horsepower. This power will be managed by a seven-speed dual-clutch gearbox and sent to all four wheels via Quattro all-wheel drive. Expect the production car – with the normal aggressive RS fittings – to debut at the Frankfurt Motor Show this September.