Audi will expand the TT line-up with three new models by 2010. There will be a Cayman-rivalling TTS in 2008, a BMW M3-chasing TTRS, and an all new twin turbo TT diesel coming in 2009.

The first to be unveiled will be the TTS. Coming in the summer of 2008, the TTS will be powered by the new four-cylinder turbo model running a version of the Audi S3’s four-cylinder turbo engine.

It’ll be available with either a six speed manual gearbox or an ‘S-tronic’ DSG automatic transmission, and as either a coupe or a roadster. All versions will get Quattro four-wheel drive.

The second to b unveiled will be the diesel version of the TT: the TT TDi. Set to be unveiled in 2009 in will be powered by a twin-turbo version of the 2.0-litre common rail diesel engine and will compete with the BMW 123d coupe.

The TT TDi will deliver 202bhp and almost 300lb ft of torque. It will also be capable of a 40mpg average fuel economy, and less than 150g/km of CO2. Also the 0 to 60 mph sprint will be made in under 6.5 seconds and will hit a top speed of 150 mph.

And finally the hottest TT in all the times will be the TTRS, a model powered by 2.5-litre five-cylinder engine producing a generous 343bhp. The TTRS will come to compete with the BMW M3.

The TTRS’ will have wider tracks than the standard car, run 20in alloy wheels and will borrow the RS4’s carbon ceramic brake discs too.