These are the first images of the all-new 2015 Audi TT Roadster, which has been spotted undergoing performance testing at the famed Nurburgring circuit in Germany.

Audi TT Roadster 2

The soft-top convertible variant of the much-anticipated third-generation Audi TT sports car appears to retain its cutesy-rather-than-macho styling, with the car spotted here wearing a low-profile black fabric roof that will tuck in behind the cockpit. The Roadster clearly boasts a more prominent backside than the coupe, and while we've not yet seen images of the car with its roof down, it's expected to sit flush in front of the boot-lid.

Audi TT Roadster 5

The new model, which is to be built off the MQB modular underpinnings that can also be found beneath the Volkswagen Golf and Audi A3, is expected to be significantly lighter than the convertible version of the second-generation TT.

The current convertible weighs between 1355 and 1490 kilograms depending on the variant. The new TT has seen drops of up to 50kg on some variants - the entry-level petrol 2.0 TFSI specification, for example, weighs 1230kg in coupe guise.

Audi TT Roadster 7

As is clear from the above image, the neat clamshell folding roof features a broad rear glass section to aid visibility, and the car also features a slimline pop-up spoiler to aid aerodynamics.

Engines are set to mimic the standard TT line, with a 2.0-litre turbocharged petrol front-drive model as well as a quattro all-wheel-drive version producing 169kW of power and 370Nm of torque. A 2.0-litre turbo diesel with 135kW/380Nm is also expected, while the top-end TTS model offers 228kW and 380Nm. Read more about the TT range and specifications.

Audi TT Roadster 1

Audi Australia was unable to confirm specific timing for the new TT Roadster, but it is likely the new model could arrive towards the end of 2015. The new TT coupe will arrive in showrooms in February.

Click here to see more images of the 2015 Audi TT Roadster.