When Audi released the RS4 in February 2005 nobody expected it to be a true competitor to BMW’s benchmark M3 coupe, but with the benefit of quattro all-wheel-drive, a boost in power, and better weight distribution, the performance sedan managed to upset its rivals. Audi has decided, however, to not produce a RS4 sedan this time around, and instead concentrate on the RS5 coupe, which is expected to debut in February next year in time for the 2009 Geneva Auto Show.

These latest spy photos show the RS5 being put through its paces on the Nurburgring, the legendary circuit that has become popular of late among carmakers for its demanding surface and use as a testing and proving grounds. The new wheels and reworked front air dam indicate the car is nearing final specification, including a prototype of the final engine that will power the car.

Previous spy shots revealed Audi has been testing the new car in Death Valley, USA. It is expected to get a new front-end treatment compared to the rest of the A5 lineup. Like the RS4, expect the final production RS5 to be fitted with large fenders and an aggressive rear-end as well.

With the release of the new generation BMW M3 Coupe and sedan and the Mercedes C63 AMG, Audi will once again be playing catch-up but it does have a few tricks up its sleeve to ensure it will be the class-leader once again. One potential powertrain option is the same 4.2L V8 as the RS4, however power will be boosted to 450hp (335kW) and it will likely get the option of Audi’s newly upgraded S-tronic dual-clutch gearbox along with a manual transmission. Other sources claim it may use a derivative of the V10 from the RS6, however this is likely to be too expensive for a car that will have to compete in price with its aforementioned German rivals.

The previous model was unable to use the dual-clutch gearbox because it was limited to just 236lb-ft (320Nm), however the latest version of the gearbox can handle torque figures of up to 406lb-ft (550Nm) and engine speeds of 9,000rpm, which could allow the RS5 engine to rev even higher than the lofty 8,300rpm in the old RS4.

Expect the RS5 to make its official debut next January at the Detroit Auto Show.