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Friday 1st March 2013


MERCEDES SLS AMG ELECTRIC DRIVE: DRIVEN

Chris goes sideways in an SLS - business as usual? Not when it's an electric one


I have driven a Tesla sports car two times - the first was educational and surprising, the second ended with a pair of black lines stretching 50 yards down a quiet country road. The initial acceleration was so intense that the tyres just couldn't cope.

But the limitations of the Tesla were the limitations of the car on which it was based, the Lotus Elise.

Different modes have a dramatic effect
Different modes have a dramatic effect
Post-Tesla the world went electric sports car mad. Audi gave us the E-Tron, Ferrari spoofed a 599 with a few Duracells under the cabin floor and pretty much everyone said they'd have an electric performance car on sale before long. But as things stand, only Mercedes AMG has managed to follow the rhetoric with some actions.

The SLS Electric Drive will go into production in May and the first customers will take delivery in July. The car has a claimed 740hp, 737lb ft of torque and a top speed limited to 155mph.

Same but (very) different
This is not an electric car like the others I've come across. The bodywork looks to be stock SLS but the carbon backbone chassis underneath houses twelve battery modules with 72 cells. And this is where we call need to start using a new vocabulary - that of the fast electric car. It has an energy content of 60 kilowatt hours and can withstand an electric load of 600 kilowatts. To my petrol-addled ears this description makes it sound like an especially potent pair of loudspeakers, but attention is regained once again by the claim of 0-62mph in 3.9 seconds.

There's a lot to take in and get your head around
There's a lot to take in and get your head around
The other dramatic spec-change over a standard SLS is the front suspension: the damper won't allow a front driveshaft so it's been completely redesigned as a push-rod system.

Mercedes claims the car will manage 175 miles on a full charge if driven carefully and that 125 miles could be expected if you use some more of that torque. Computer simulations show that the car would run two full laps of the Nordschleife flat-out, but not complete a third. The target lap time is under eight minutes - which is punchy give the car weighs 2,200kg. The batteries alone weigh 548kg.

Early adopters
This is of course a rolling showcase for future technologies as much as a sports car to stand comparison against fossil powered equivalents. It is the very cutting-edge of battery, motor and torque-vectoring technology and yet in terms of kerbweight, range and cost (nearly 400K) it remains uncompetitive with its immediate rivals in the sector.

They're looking at an eight-minute 'ring lap
They're looking at an eight-minute 'ring lap
All of that goes out the window the moment you pull back the familiar SLS gear lever into D and gingerly prod the accelerator. The car creeps the first few yards in its Comfort setting and swooshes forwards as you try and find a correlation between right foot movement and acceleration. The throttle pedal travel is long and the car is limited to just 590hp in this and Sport mode, and top speed is pegged at 125mph. There are two 'sound modes'. One provides a kind of new-age soundtrack through the 11 speakers and is part-Tron, part real-time representation of how the car is moving. It's very subtle and I barely noticed it, mostly because the car itself was busy blowing my mind. You can switch it off completely if you wish.

Comfort gives way to Sport mode, which gives a tighter chassis response through the torque vectoring system and sharper steering The headlines are all about the SLS's electric powertrain, but the chassis systems are just as impressive and certainly more pertinent to the way cars will be engineered in the near future.

No V8 but the numbers come up just as fast
No V8 but the numbers come up just as fast
Jekyll and Hyde
Because each wheel has its own motor and gearbox the car can accurately control individual wheel speed in any situation, and this means the chassis team can programme all manner of chassis behaviour, feel and character into the car. So whereas a conventional sports car chassis offers different levels of electronic intervention and perhaps damper stiffness, the SLS feels profoundly different in Comfort than it does in Sport Plus. The steering, power delivery and grip front-to-rear seem to belong to two completely different cars.

Sport Plus is the mode you really want. Full power, full torque, 155mph and slip angles: this car will paint black lines in the dry. It hides its mass very well because the centre of gravity is low and in the centre of the car. The standard SLS Michelins tend to let go at the front first, but the torque-vectoring gamely tries to keep everything neutral - the only problem being that your inputs to trim the car's line sometimes conflict with the computer's. But you quickly learn to adapt to what it wants and doesn't want. And then it dawns on you that you're driving an electric car very, very fast. The carbon ceramic discs that felt supreme in the 1,650kg standard car are at their absolute limit in this one.

No V8? No problem
Switch the traction control off and it's a monster. I mainly drove it in the wet and you could pull monstrous slides - a completely surreal experience with zero engine noise. Straightening the car back into line after the slide was challenging because the computer wants to get involved, but again you learn to adapt.

As for battery life - well, we hooned about using all the performance for an hour and consumed around 65 per cent of the charge. I didn't expect it to last that long. Based on that the 125-claimed range in normal driving seems perfectly achievable, driven slowly that rises to around 175 miles.

I still can't believe that Mercedes AMG has delivered on the promise with this car. It will go into production in May and will cost around 400K. That is crazy money for most of us, but it previews what will be possible very soon. It is the fastest electric car ever made and it happens to offer all the comfort, practicality and style of an SLS. It's unlike anything I've driven before and it left me grinning like a child. Electric cars shouldn't do that.


MERCEDES SLS AMG ELECTRIC DRIVE
Engine:
4x electric motors, 72-cell lithium-ion 60kwh battery
Transmission: One per axle
Power (hp): 740 (combined)
Torque (lb ft): 649 (combined)
0-62mph: 3.9sec
Top speed: 155mph (limited)
Weight: c. 2,200kg
Range: c. 155miles
CO2: 0g/km
Price: c. 400K

Author: Chris Harris