Upcoming flagship super-sports car snapped at the 'Ring, ahead of a potential reveal in Frankfurt.

A Mercedes-AMG GT R prototype believed to be the upcoming Black Series version has been spotted again doing rounds at the famed Nurburgring circuit in Germany.

Compared to the GT R and GT R Pro, the Black Series gets a revised front bumper design incorporating a more aggressive splitter, along with large flics that extend from the grille through to the front wheel arch.

At the rear, the centrally-mounted exhaust tip of the GT R has been submitted for two sets of two pipes sticking out on either side of the bumper.

The front guards also appear to be wider, particularly when viewed from the rear, while the fixed rear wing looks to be at a more aggressive angle compared with the GT R and GT R Pro.

Power should continue to come from the company's now ubiquitous 4.0-litre bi-turbo V8, though expect a bump up from the GT R's 430kW and 700Nm – the AMG E63's 450kW and 800Nm could be a guide.

It's unknown precisely when Mercedes plans to reveal the Black Series version of its AMG halo car, though it's suggested by various reports it will debut either late this year or early next.

Stay tuned for all the latest, and click on the images for the full gallery.