At the 2013 Geneva Motor Show German tuner Carlsson will present a new kit for the Mercedes CLS63 AMG with up to 700 horsepower, and an Autobahn-tested top speed of 340 km/h. The CK63 RSR is one of the fastest and most powerful four-door sedans in the world.

Save the 20-inch Carlsson 1/10 wheels, lowered ride height, and a few aero parts such as a front spoiler lip, more prominent rear diffuser, and new round tailpipes, the RSR looks pretty much like the standard CLS63. Same goes for the interior. You get some new leather and Alcantara, aluminum pedals, and special floor mats, but there is no clue on what a monster this car really is.

It is only when you open that taps and unleash the RSR’s modified V8 engine that you realize you are dealing with an extraordinary car. The tuner has fitted the M157 AMG engine with a bespoke steel exhaust system featuring 200-cell metal catalytic converters, and new maps for its electronic brain. The result is 700 horsepower (515 kW) and over 1000 Nm (741 lb-ft) of torque, which translates into a 0 to 100 km/h time of 3.9 seconds, and as mentioned, a top speed of 340 km/h.

To keep this beast in check, Carlsson has employed some seriously large brake discs with multi-piston calipers, and a set of adjustable coilovers.