Hardcore sports coupe hits iconic circuit wearing heaps of camouflage and quad-exhaust outlets.

A prototype believed to be a more extreme 'Black Series' version of the Mercedes-AMG GT has been spied again, this time during performance testing at the Nurburgring race track in Germany.

Compared to the prototype snapped in September, this vehicle is sporting a more aggressive aerodynamic setup, including a more pronounced front bumper and splitter with incorporated flics, and a larger rear wing.

Out the back we can see a set of pre-production quad tailpipes, which is a dead giveaway of a new variant given the current GT R flagship has a centrally-mounted arrangement.

The exhaust could hint at a revised engine setup, which could see a more powerful version of the 4.0-litre bi-turbo V8 that does service across the AMG GT range.

At the moment the most powerful GT variant is the GT R, which offers 430kW and 700Nm. This 'Black Series' version could up outputs to 450kW and 850Nm – the same as the AMG E63 S.

Should the flagship GT get the hi-po E-Class' engine tune, it could also add all-wheel drive for the first time to handle the extra torque, though nothing is confirmed at this stage.

AMG boss, Tobias Moers, has already confirmed the company is developing a GT Black Series for 2020, and it's likely this is a prototype for that model.

Historically, Black Series versions of AMG models have featured increased power outputs and enhanced aero kits compared to their 'standard' counterparts. Model lines that have received the Black Series treatment include older-generation AMG versions of the CLK, C-Class and SL, along with the SLS supercar.

Given the 2020 launch date earmarked by Mercedes-Benz's performance division, expect to see the GT Black Series to debut in production form sometime late in 2019, and hit the market the following year.

Stay tuned to CarAdvice for all the latest, and click here for the full image gallery.