The Mercedes-Benz SLS AMG supercar you're looking at may have a garish paint scheme, altered cooling vents, aerodynamically optimized wheels and deeper bumpers, but it's no tuned-up special. At least, not in the traditional sense.
This is the SLS E-Cell – a new, very yellow electric supercar that's in development at AMG in Germany. Sales are set tentatively for late 2012. Just 1,000 cars will be offered to "preferred customers" at a price that, Mercedes says, will be "beyond" that of the gasoline-powered SLS (which will go for around $225,000).
The E-Cell uses the same aluminum bodyshell as the gas SLS, albeit with a totally flat undertray that reduces drag. However, some serious changes have been made to the SLS's mechanicals to accommodate the complex electric driveline, lithium ion batteries, associated wiring and new ancillaries, resulting in a front-to-rear weight distribution of 46/54 and a center of roll that's 24mm lower than that of the gas-powered SLS.
Stuttgart's new-age supercar doesn't just rely on one electric motor but four individual ones placed low at each corner of the car, each capable of 12,000rpm. They combine to produce 526hp and 649ft-lbs of torque. By comparison, the SLS's naturally aspirated 6.2-liter V8 delivers 563hp and 479ft.-lbs. And, whereas the SLS places all of its drive through the rear wheels, the E-Cell gets it down via two individual transmissions from Getrag – one mounted on each axle – to all four wheels.
Other changes? The packaging of the two motors up front has required a rethink of the front suspension. The standard double wishbones make way for a multi-link arrangement with space-saving pushrods. The rear multi-link setup remains largely unchanged.
The electric motors – off the shelf items from Swiss specialist Brusa – draw 400 volts from banks of lithium ion batteries mounted under the hood, in the transmission tunnel and in the space normally taken up by the SLS's fuel tank. The battery packs are from Deutsche Accumotive, a joint venture formed last year between Daimler and alternative energy specialist Evonik. Consisting of 324 individual cells and weighing 992lbs, they have a rating of 40 amp hours and a capacity of 48 kilowatt hours.
Although it's still just a prototype, this SLS E-Cell already feels like a regular production model. It feels solid enough to make you wonder what AMG has yet to do before the car is signed off. If the quality and the togetherness of this car is an indication of what Mercedes will place on sale in two years' time, the electric car competition is going to have to take note.
With only one gear ratio, the SLS E-Cell's shift lever has been replaced by three buttons marked D-P-R along the center console. Engage D, apply a hint of throttle and this high-tech Mercedes-Benz glides off with only the muted roar of tire on asphalt and the occasional ping of loose stones thrown up into is wheel arches.
The E-Cell's throttle pedal is sprung more firmly than that of the regular SLS, presumably to deter you from unnecessarily reducing your limited range; ours reads 88 miles at full charge.
Around town, this low-slung two-seater feels oddly pedestrian. You simply point and squirt between traffic lights, being careful to back off the throttle as early as possible to recoup maximum energy while coasting. But, as we do that, our loud-looking, silent-driving SLS E-Cell causes bystanders to stare in utter confusion.
The inherent quietness of this car serves to amplify otherwise undetectable sounds – the whirring of the electric steering pump, for example. You're also more aware of changes in the road surface and the roar of the tires altering in pitch as the road opens up, speeds rise and the wind begins to whistle around the door mirrors.
The Atlantic Ocean Road along Norway's western coast i smooth and gently curving. It's home to the spectacular Storseisundet Bridge, which looks like nothing short of a two-lane rollercoaster as you approach it. But its steep ascent is no problem for the E-Cell, whose deep reserves of torque give it an almost invincible feel.
And, you'll be genuinely shocked by he violence of acceleration you get on burying the throttle. Although it weighs a good deal more, the E-Cell kicks with a force comparable to the SLS AMG at full song in low gears – and it does so instantly. The thrust is seamless, virtually silent and more brutal than its claimed 0-62mph time of 4.0sec suggests. Foot planted, you'll reach 124mph in 11.0sec. To preserve charge, the SLS E-Cell's top speed is limited to 155mph, but its theoretical top speed is 168mph.
The key to driving the SLS E-Cell smoothly – and maximizing its range – lies in learning to use its clever steering wheel paddles to cycle between four levels of brake energy regeneration. Although the car has only one gear ratio, on the way into a corner this variable recuperation system makes it feel as though you're changing down through a conventional gearbox, slowing the car with engine braking. So in the lowest recuperation setting, the car simply coasts when you lift – as if it were in top gear at cruising speed – but "shift" toward the highest level and here's more discernible retardation as more kinetic energy is captured, converted and stored. It's the smartest energy regeneration solution that we've come across on any electric vehicle to date.
The SLS E-Cell doesn't handle quite as well as the gasoline SLS at this early stage in its development, but given that the prototype weighs close to 4,400lbs, its dynamics are a revelation. At moderate cornering speeds, the car has excellent body control and holds its line remarkably well. That low center of gravity helps, as do the grippy tires (no low-resistance rubber here) and a communicative chassis.
One area where it really excels is traction. With a motor at each wheel, it hurtles out of corners with a level of athleticism equal to anything. If there is a weak link right now, though, it is the steering. The electric system has a high gearing but it lacks the responsiveness of the regular SLS's hydraulic setup. It also fails to provide enough self-centering after you've wound on a good amount of lock, laving you to feed the wheel back yourself exiting slower corners.
Nonetheless, our first drive of Mercedes-Benz's SLS E-Cell suggests that the production version could be one of the most well-executed EVs we've yet seen. We don't know for sure if it is capable of hitting the 93-mile range it's said to be capable of. Nor can we confirm whether the claimed eight-hour charge time is possible on home outlets. Still, the E-Cell already meets the lofty performance targets set out when it first began development under former boss Volker Mornhinweg – and considering those are Mercedes AMG performance targets, that's no mean feat.