Why The CLE 646 Is Mercedes AMGs Ultimate Track Weapon

Thirty units. That is the entire production run, and every single one was sold before Mercedes-AMG even pulled the covers off the CLE646 Special Edition. This factory-built track weapon is the second entry in the Mercedes-Benz Mythos series follows the roofless, windscreen-less PureSpeed. It arrives with a wild body kit, active aero and packs a serious punch.

The Mercedes-AMG CLE646 Special Edition is, for me, the epitome of AMG. This vehicle came about because rational engineers dreamed of a very irrational vehicle. We made that dream a reality – in the form of maximum driving dynamics and an unparalleled driving experience
– Dr. Stefan Weckbach, chairman of the board of management of Mercedes-AMG GmbH

Muscle bound

The track machine is based on the CLE coupe but transformation starts with the shell itself. Mercedes-AMG widened the track by 60 mm at each axle, then wrapped those extended dimensions in carbon-fibre. The fender flares integrate air vents and swallow 20-inch forged wheels shod with 305/30 and 335/30 track-focused rubber. Ride height drops 22 mm at the front, 16 at the rear.

The bonnet, roof, rear diffuser, boot lid, longitudinal frame rails, and that manually adjustable rear wing all carry the woven finish of exposed carbon. Even the rear glazing is polycarbonate, and the 12-volt starter battery is a lighter unit. Every unnecessary gram was dropped and every surface is functional. Lightweight bucket seats with are fitted, along with a roll cage that increases the body’s torsional rigidity. Lightweight carbon fiber door panels are also included

As if the body isn’t dramatic enough… The Mojave Silver Magno covers everything forward of the B-pillar; everything aft is Obsidian Black Magno. AMG crests sit on both doors. The wing endplate carries a subtle reminder of just how limited the CLE646 is.

Adjustable aero

Not only does the body look hard-as-nails, it delivers functional results, too. Downforce exceeds 250 kilograms at the 310 km/h. But you’ll have to haul out the toolkit. The front splitter adjusts via three screws between ‘Street’ and ‘Race’ positions. In Race, it extends downward to form an inverted wing profile beneath the nose, accelerating airflow through the Venturi tunnel and pressing the front axle into the tarmac. The result is sharper turn-in and higher lateral grip.

With the diffuser extended, the central section of the carbon rear wing moves to match, to restore aerodynamic balance for circuit work. Fender louvres ventilate the wheel arches of air pressure. These are fed by ducts beside the headlights that route air over the arches and through the louvres. Canards on the bumper sides clean up airflow, adding front downforce while directing cooling air toward the brakes. Beneath the car, a flat underbody with longitudinal fins accelerates airflow.

Packing power

Under the lightweight bonnet is a development of the M177 engine. This Evo version of the twin-turbocharged 4,0-litre V8 cranks out 475 kW (646 hp, hence the name), with 850 N.m of torque. A flat-plane crankshaft has less rotating mass, which allows for quicker revving, and a sharper response to throttle inputs. The exhaust is a collaboration with Akrapovič, titanium from the catalysts back, tuned for flow and for an “emotional” soundtrack.

The AMG Speedshift transmission has nine ratios and has been programmed for rev-matched downshifts. Launch control is recalibrated for the rear-drive-only driveline. Thanks to launch control the sprint from rest to 100 km/h takes 3,9 sec, to 200 km/h takes 11,4. Top speed is 310 km/h.

The usual 4Matic+ system is gone. Power reaches the road through the rear axle alone, reducing mass and altering the car’s character. An electronically controlled limited-slip differential manages torque distribution across the rear wheels, enabling controlled drifts. The traction control can be adjusted, allowing the driver to pre-select the slip at the wheels in nine stages.

Suspension and Brakes

The coilover suspension is a joint development between Mercedes-AMG and KW automotive, the German specialists whose aftermarket dampers have underpinned countless racing programs. Four-way adjustability means independent control of low- and high-speed compression and rebound.

Braking is handled by an AMG ceramic composite system with 420 mm front discs and six-piston fixed calipers. The rear items are 360 mm with single-piston floating calipers. Gold paint identifies the calipers as the high-performance specification. Ducting from the front bumper and air guides keep temperatures in check during heavy track work. The ceramic construction reduces unsprung mass and rotating inertia compared with conventional iron discs.