Audi’s current A6 has been on sale for almost two years now, but we’re still at least a year away from the release of the potent RS 6 super-sedan and Avant wagon. Originally thought to debut at September’s 2007 Frankfurt Auto Show, latest reports suggest that its release date has been pushed back to June of next year.

The BMW M5 and Mercedes-Benz E63 AMG have already proven there's potential in both the sales race and on the track, but we’re still waiting to see what Audi can do to topple the former RS 6. Commonly referred to as a "wolf in sheep’s clothing", the original RS 6 sedan was chosen by many motoring mags as the pick of the bunch over the BMW and Mercedes competition.

Spotted on numerous occasions undergoing final testing at Germany’s Nürburgring, often with an M5 in tow, the next RS 6 is rumored to feature the same 5.2-liter V-10 found in the S6 but with a turbocharger bolted on for extra kick. Early estimates put its output in the vicinity of 520-550 horsepower, enough to give it a significant power advantage over its rivals.

This image, sourced from an Audi enthusiast forum, show that the RS 6 will differ significantly from the lesser S6 thanks to an aggressive blacked out rear diffuser housing large twin-oval exhausts, large intakes in the front bumper and wider fenders to conceal the extra width of the performance tires.

No word yet if the car will be sold in the U.S.

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