A Mercedes-AMG C 63 R development version has been spotted being tested at the Nürburgring recently. The test mule wore a large rear wing and a prominent front spoiler, suggesting it will produce genuine downforce to enhance track performance and hinting at a more powerful version of the C 63’s ‘hot-vee’ twin-turbocharged V8 under the bonnet.

The most powerful C 63 presently, is the C 63 S, which produces 510hp from its 4.0-litre unit. But the 585hp GT R that shares the same unit, indicates that significantly more power can be extracted from the C 63 S’ engine. The GT R’s 4.0-litre petrol engine uses different turbochargers, reworked engine mapping and a higher compression ratio to offer the additional grunt, but it's not yet known whether the C 63 R will get exactly the same specification of engine.

Like the AMG GT R, the C 63 R will shed some weight due to the use of carbonfibre parts and possibly, a set of aluminium wheels and a titanium exhaust system. The results will make for a car that’s both, significantly quicker off the line and faster around corners than the C 63 S.

While not confirmed by Mercedes, a hotter version of the C 63 has been expected for some time. Originally thought to come in the form of a C 63 Black Series, it now seems that Mercedes will opt to use its R badge to name its extra-hot coupé.

The Black Series model name is not expected to return to production until an AMG GT Black Series is launched in the coming years, as previously suggested by AMG boss Tobias Moers. "It won’t be here soon because the Black Series cars tend to come towards the end of a car’s production cycle, but an AMG GT Black is a car we must do,” he said. Mercedes is likely to stick with its ‘S’ and ‘R’ naming conventions, as demonstrated by the AMG GT S and GT R models, until that first new Black Series model has been launched. The C 63 R will rival the BMW M4 GTS when it debuts next year.