In a letter to its German dealer network, Audi reveals new performance and styling details of the forthcoming Audi TT RS. has received from a reliable source a copy of a letter from Audi to its German dealers which includes more details of the upcoming Audi TT RS.

The Audi TT RS will feature a new 5 cylinder, 2.5 liter TFSI mated to a 6-speed transmission churning out a remarkable 340 hp and 450 Nm of torque. The new engine will make the TT RS one of the most fuel efficient sportscars around. Audi claims its direct-injection FSI technology will keep consumption under 10 liter/100km while still making the car capable of doing 0-100km in 4.5 seconds.

The exterior will come with front air intakes, 18" aluminium wheels and two twined, oval shaped exhausts pipes at the back. Interior design will be pure RS - with RS insignia on the instrument panel and the onboard computer menu. The cabin remains classic Audi metallic-themed with aluminium air vents against a black dashboard. The TT RS comes with Alcantara/leather sports seats with a distinguishing silver stitching.

 The RS version of the TT will also be available as either a coupe or roadster. No details on pricing are available yet.

The accompanying photos are recent spy shots taken of the Audi TT RS at Nürburgring in Germany.

The TT RS is expected to be launched in the third quarter of 2009.

Gallery: New Audi TT-RS Details Leaked