Mercedes-AMG SLS E-Cell

What is it?

The SLS E-Cell. A very new, very yellow plug-in electric supercar that is undergoing intensive development at AMG’s skunk works on the outskirts of Stuttgart, with sales set for late 2012.

The SLS E-Cell driven here is the first running prototype Mercedes-Benz’s AMG division has constructed as part of a three year development program for the new car.

As its familiar appearance suggests, the SLS E-Cell uses the same aluminium intensive body shell as the SLS AMG with some slightly different detailing, including a totally flat undertray to lower the overall drag co-efficient.

However, some serious changes have taken place underneath. In a move that provides it with a weight distribution of 46:54 front-to-rear and lowers the crucial centre of gravity by 24mm over its petrol engine sibling, Stuttgart’s new age supercar uses four individual motors – one at each corner.

They combine to produce 526bhp and a mighty 649lb ft of torque. By comparison, the SLS AMG’s naturally aspirated 6.2-litre V8 delivers 563bhp and 479lb ft.

But while the SLS AMG places its drive through the rear wheels, the SLS E-Cell gets it down via two individual transmissions from Getrag – one mounted on each axle - to all four wheels. Mercedes-Benz has also provided it with torque vectoring.

Other changes? The packaging of the two motors up front has also required a rethink of the suspension; the standard SLS’s double wishbones makes way for a new multi-link arrangement complete with space saving pushrod dampers. The rear multi-link set-up, on the other hand, remains largely unchanged.

The electric motors draw from a bank of lithium-ion batteries mounted under the bonnet, down the middle of the floorpan and behind the seats. They have a capacity of 40Ah, are rated at 48kWh and add a hefty 450kg to the car’s weight.

Recharging is via a multi-pin 240 volt plug, with total recharge time of eight hours at 16 amps. With an external 240 amp charger this can be reduced to less than one hour, although the values are in no way final.

The SLS E-Cell also uses a sophisticated brake energy recuperation system to continually recharge the battery pack with electricity created under braking.

The brakes themselves use lightweight carbon ceramic discs – 402mm in diameter up front and 360mm at the rear. They’re the same hydraulically operated units available as optional equipment on the SLS AMG.

What’s it like?

Press the start button of the SLS E-Cell and its futuristic looking instrument panel lights up in an impressive burst of blue and green. But there’s no sound. No nothing...

Applying the small amount of throttle sees the hi-tech Mercedes-Benz glide away from standstill with only the muted roar of tyres over bitumen, the action of the suspension and the sound of loose stones being thrown up into the wheel arches providing evidence of progress.

You’re also more aware of changes in the road surface – the roar of the tyres, which constantly alter in pitch as the road begins to open up and speeds rise. Wind noise around the exterior mirror housings also becomes a continual factor as speeds rise.