For anyone worried that Mercedes might be watering down its sportiest cars by extending its AMG range beyond rip-snorting V12 and V8 sedans and coupés, Brabus’ 650hp version of the Mercedes C-Class executive sedan could prove the antidote.

The Brabus has two extra doors, two extra cylinders and an extra 283hp (hence its 650 moniker). The resulting performance figures are ferocious -- 0-100km/h in 3.8 seconds and a top speed of 320km/h.

But the Brabus is more than just a brittle road rocket. Its tuning is covered by a three-year warranty and the cabin is as comfortable as it is sports-focused.

The steering wheel and certain panels of the seats are finished in anti-slip Alcantara to ensure the driver stays in control. The rest of the cabin is finished in high-quality black leather with yellow contrast stitching, while door panels and dashboard elements are finished in polished or lacered carbon fiber.

Outside, to ensure the car stays planted to the road, the 650 has a reworked nose and tail, also formed from carbon fiber and designed to stop lift on the front or rear axles at high speeds.

And with a nod to being a good neighbour, the special sports exhaust system has a 'coming home' mode, which can be engaged to keep the car's noise down when in residential areas or pulling into a driveway.

 As well as a completed car, Brabus can also apply all of the tuning elements showcased in the 650 to an existing Mercedes-AMG C 63, whether a sedan or the even more practical station wagon.

 The car will be unveiled at the Geneva Motor Show on March 1 alongside a new customised take on the Smart Fortwo cabrio, details of which are being kept a carefully guarded secret.

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