A mysterious Audi TT prototype has been spied on the Nürburgring.

A mysterious Audi TT prototype has been spied on the Nürburgring.

Caught by TouriClips, the mysterious model is rumored to be a mule for the 2016 TT-RS. Unfortunately, this is hard to confirm as the car appears to be wearing an old TT S body.

Nothing is official but the TT-RS is expected to use the same turbocharged 2.5-liter five-cylinder engine as the RS3. Quattro GmbH Managing Director Heinz Hollerweger has previously said it will have an output of "around 360 bhp (268 kW)" but he also hinted at a Plus variant with up to 400 bhp (298 kW).