Mercedes' winged wonder on track

Unofficial acceleration figures have the GT3 sprinting from zero to 100km/h in 3.7 seconds. Top speed is more than 300km/h. Photo / Supplied

Mercedes-Benz has officially opened the order book for the track version of its "Gullwing" SLS AMG.

The modified model wears the SLS AMG GT3 moniker and will be delivered before the start of GT3 competitions in 2011.

It is listed at €396,460 ($722,000). Testing began in June and continues through to the car's first competitive event, a race at Germany's Nurburgring at the end of next month.

The lightweight racing version of the SLS AMG has been developed by AMG and motorsport specialist HWA, the company responsible for the AMG-Mercedes DTM race team.

Says Mercedes-Benz motorsport chief Norbert Haug: "The Mercedes SLS AMG GT3 marks the beginning of a new era in Mercedes-Benz customer motorsport.

"This is an exciting and spectacular sports car for dedicated private teams and talented private drivers."

Long-time DTM driver Bernd Schneider has been doing most of the test drives. He says: "The SLS AMG has excellent genes for being successful in motor racing. Even on my first fast laps, it was obvious that the GT3 version of the gullwing model has just what it takes to be a big hit on the racetrack.

"The combination of optimum weight distribution, a low centre of gravity, a powerful AMG V8 engine and efficient aerodynamics already indicates that the SLS AMG GT3 will be very competitive."

Engineers focused on aerodynamic performance and modified the entire bodyshell. The new front apron has a splitter, the bonnet gets a central cooling air vent, there are wider front and rear wings, the sideskirts get cooling ducts for the rear brakes and the rear gets a diffuser and adjustable aerofoil.

Motorsport's international governing body the FIA will rule on the maximum output of the AMG 6.3-litre V8 engine the "balance of performance" principle.

This is intended to ensure all the racing cars taking part have an equal chance. The classification process, during which the kerb weight is also determined, will be completed early next year.

The engine in the road-going SLS AMG delivers 420kW at 6800rpm and 650Nm of torque from 4750rpm via a seven-speed twin-clutch sequential gearbox.

As defined in the FIA GT3 regulations, the engine is virtually identical to that of the series production vehicle. Thanks to its low weight, unofficial acceleration figures have the GT3 sprinting from zero to 100km/h in 3.7 second, or a 10th of a second quicker than the standard car. Depending on gear ratio, top speed is more than 300km/h.

The GT3 will use a sequential six-speed racing transmission with steering wheel shift paddles, an integrated multi-disc locking differential and traction control.

As in the standard SLS AMG, the transmission is located at the rear axle. The engine and transmission are connected by a torque tube within which a carbon-fibre shaft rotates at the engine speed, as in the roadgoing version. The transaxle design ensures favourable weight distribution optimising handling and traction.

In a system that is largely the same as the one used in the roadgoing cars, the wheels are located by a double-wishbone suspension of forged aluminium at the front and rear.

Adjustment facilities for the springs and shock absorbers, the suspension height, the stabilisers, the track width and camber allow an individual setup for the racetrack.

The rack-and-pinion steering has been modified for a more direct ratio. Behind the central-locking AMG 18-inch light-alloy wheels, a steel braking system with racing ABS ensures outstanding stopping power.

Like the standard gullwing, the racing version features a dashboard in the shape of a powerful wing section to give the impression of width. The steel roll cage offers a high level of safety for the driver as well as further stiffening the aluminium spaceframe.

In a set-up similar to that of the Mercedes-Benz DTM vehicles, the seat shell is located in a high-strength carbon-fibre safety cell. The cell is bolted to the roll cage and the aluminium spaceframe, and offers far greater protection for the driver.