Mercedes-Benz has kicked off a high stakes battle for electric performance car supremacy with the unveiling of the definitive production version of its SLS AMG Coupé Electric Drive at the Paris motor show.
Described as the world’s most powerful series production electric car, the new two seater shares its exterior styling, including signature gullwing doors, with the more conventional combustion engine-propelled SLS AMG, first introduced to the Mercedes-Benz line-up back in 2009.
But underneath its familiar looking bodywork the SLS Electric Drive adopts a hi-tech driveline consisting of four synchronous electric motors placed at each corner where they drive the individual wheels, providing it with permanent four-wheel drive.
Together, the four electric motors, each weighing 45kg, deliver a total of 740bhp – 177bhp more than the standard rear-wheel-drive SLS AMG’s 6.2-litre V8 petrol engine.
The electric-powered Audi R8 e-tron, which is tipped to cost less — up to half the price of the new Mercedes-Benz — when it goes on sale in early 2013, packs a claimed 376bhp.
The SLS is equipped with two separate gearboxes that provide direct drive to each axle, along with a new AMG Torque Dynamics system, which provides selective drive to individual wheels depending on prevailing traction in three different modes – comfort, sport and sport plus. The Electric Drive is claimed to reach 62mph from standstill in 3.9sec and electronically limited 155mph top speed.
By way of comparison, the standard SLS AMG reaches the same benchmark in an official 3.8sec and extends to 317km/h without restriction.
The storming performance can be accompanied by what Mercedes-Benz describes as a typical AMG sound that is tailor made for each driving situation with the press of a so-called “power” button. The synthetic sound is played through 11 speakers located around the cabin.
Energy for the electric motors is provided by a 60kWh lithium-ion battery pack, developed in co-operation between Mercedes-Benz’s AMG performance car division and its British-based High Performance Engines off-shoot, responsible for the engineering of the 2.4-litre V8 Formula One-specification engine and KERS (Kinetic Energy Recuperation System) unit used by the Mercedes-Benz, McLaren and Force India teams.
With a weight of 548kg, the liquid cooled battery is mounted within the transmission tunnel down the centre of the cabin, and behind the driver and passenger seats in the space dedicated to the fuel tank in the standard SLS AMG. It consists of 12 individual modules, each comprising 72 cells. The cells are supplied by Korean-based company, SK Innovation.
A full charge on standard mains power takes up to 20 hours, although this can be reduced to three hours using an optional wall box, which provides a 22kW quick charge function. As in Formula One racing, the battery is also charged on the run by recuperated energy created under braking and during in-gear coasting. The driver can alter the level of energy that is recovered via steering wheel-mounted paddles.
To offset the weight of the battery, AMG has introduced new lightweight construction for the SLS Electric Drive, eschewing the aluminium structure of the standard model for a more advanced aluminium and carbonfibre arrangement, first revealed at last year’s Frankfurt motor show. Other weight-saving measures include standard carbonfibre ceramic brake discs measuring 402mm up front and 360mm at the rear.
To accommodate the drive being direct to the front axle, AMG has thoroughly redesigned the front suspension, with the standard double-wishbone system making way for a pushrod arrangement using horizontally mounted dampers and springs. The steering also eschews the existing hydraulic actuation for a new speed-sensitive electro-hydraulic system. The standard wheels are 19-inch with 265/35 profile tyres up front and 20-inch with 295/30 profile at the rear. They come in a unique five speed design exclusive to the SLS Electric Drive.