Mercedes-Benz SLS AMG Black and Electric 2013 Review - International

Not so much?
>> Easily disturbed by bumps
?>> Only E63style acceleration
?>> Small step up for a Black Series?

Mercedes-Benz SLS AMG Electric Drive
What we liked?
>> Unbelievable traction
?>> New standards of grip
?>> Not remotely slow

Not so much?
>> Heavy beastie
?>> Artificial noise is too quiet
?>> Only makes two laps of the Nordschleife?

OVERVIEW
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It’s effectively a moderately softened GT3 car for the road, with more power, more grip, more downforce and, not surprisingly, it’s mega fast.

Then there is the SLS Electric Drive, built off the very same SLS but setting standards of mid-corner grip and drive that even the vaunted Black Series can’t match.

It turns out that electric cars aren’t all about saving fuel and if those pushing the electric-car argument had lead with this car instead of things like the Nissan LEAF, there probably wouldn’t be any argument any more.

Both of these cars post big numbers, ripping to 100km/h in less than four seconds and whipping around the Nurburging Nordschleife in times that would embarrass many a helicopter pilot.

They just go about it in very, very different ways…

Down in Australia (and here comes the debate again), Mercedes expects that to jump to somewhere in the high $600s for its five confirmed customers and maybe more for those on the periphery who are scrambling to climb onto the list.

But if you think that’s stiff, the SLS Electric Drive will set an environmentally friendly German speedster back an astonishing €416,500. If a €250K Black Series ends up being the best part of 700 grand here, you can only shudder to think what the number next to an electric SLS might look like. It may be a blessing in disguise that it won’t be built in right-hand drive, then.

The SLS Black Series is the fifth of AMG’s Black Series models and the fastest, too. It’s based on the SLS GT3 racing car that just cleaned up at the Bathurst 12 Hour race in the hands of Bernd Schneider, who also developed the road car in question.

It has had its DIN weight pulled down to 1550kg, it has more power (at 464kW) from its 6.2-litre V8 engine and it’s essentially sharper everywhere.

It’s sharper inside, too, where a thinly padded carbon-fibre seat will gouge your ribs. There is a bit of a carbon-fibre theme here, with the bonnet, the diagonal underbody braces, the torque tube connecting the engine to the transaxle and the panel behind the seats all made of what Benz calls “motorsport grade” carbon-fibre.

There’s plenty of Alcantara inside (it’s lighter than leather), including all around the flat-bottomed steering wheel. The central cushions on the seat are Alcantara, too, for better grip in corners.

One of the normal highlights of Benzes is their Comand APS multi-media system, but that’s been removed from the Black Series in the chase for more performance. And, on a racetrack, you’re supposed to know which way to go.

You can put it back in if you like, together with the reversing camera, but it will cost you, as will a Bang & Olufsen sound system.

The SLS Electric Drive is significantly heavier than the Black Series and with 1000Nm of torque, Benz has decided it doesn’t need to skimp on the luxuries. At that price, you’d bloody well hope not.

It gets the most extravagantly trimmed of the SLS’s seat options, has plenty of carbon-fibre trim throughout, scores seat heating and sees the welcome return of the multi-media unit.

But there’s a twist, with the multi-media system also delivering info on everything to do with the electric drive system, including the range, the battery charge, the recuperation level, which motors are doing the work and even a lap timer.

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The engine is always the starting point and it delivers 44kW more than the standard SLS. Because AMG had to lift the revs (to 7400rpm) to gain the power, it has actually lost torque, dropping from the stock car’s 650Nm to 635Nm – developed 750rpm higher at 5500rpm. Still, it revs out to 8000rpm where the stock car’s engine is all over at 7200.

AMG had to redesign the cam profiles to deliver the higher revs and it tweaked the air-intake system, too. Oddly, the naturally aspirated V8’s multi-point fuel delivery system lives on in an era of direct-injection. There have been plenty of other upgrades, though, including the entire water and oil delivery system, strengthened connections on basically everything inside the block and new crankshaft bearings.

There is also an innovative damper – much like a shock absorber – inside the engine bay, connecting the engine block to the body to stop it from changing the load on the suspension under hard cornering.

It gets a very light titanium exhaust system as part of its weight-saving measures, with the exhaust engineered to be especially loud between 5500rpm and 8000rpm.

With its 70mm pipes, the exhaust system weighs just 17kg – 13kg lighter than the standard SLS exhaust even though it uses the same exhaust headers.

Where the standard SLS uses a sand-cast alloy torque tube to do the joint jobs of housing the spinning prop shaft from the engine to the rear-mounted gearbox and to add chassis rigidity, the Black Series has a tube that’s basically the same shape but made from carbon-fibre. At 13.3kg, it has neatly halved the weight of the standard production version.

There’s a carbon-fibre reinforced plastic driveshaft as well, which weighs 4.7kg, and AMG has even used a lithium-ion 12-volt battery to save 8kg over the usual item. All up, the Black’s 70kg lighter than the standard model.

While the standard seven-speed dual-clutch gearbox still sits inside a housing in front of the rear-mounted differential, its innards and its software are largely the same, just a touch faster.

The biggest difference to the performance of the car and the way it feels is that the final-drive ratio is about 20 per cent shorter. This explains the Black Series’ lower top speed compared to the normal car, but also goes a way to explaining the sharper acceleration.

It also runs an E Diff, or electronic differential lock, to give better drive out of corners, and that feeds directly into the same set of sensors and systems that govern the three-stage ESP.

While it still runs the SLS’s double wishbone suspension layout all round, the Black Series has basically new or tweaked bits everywhere else.

The three-stage damping is gone, replaced by a choice of Sport or Sport + for the suspension dampers, and the spring retainers are now threaded so the spring rates can be adjusted for track work.

The track widths have been pushed out by 20mm at the front and 24mm at the rear and part of that is to accommodate new wheels with Michelin’s all-new Pilot Sport Cup 2 tyre (also found on the upcoming Porsche 918), with 275/35 R19s at the front and 325/30 R20s at the rear. They’re mounted on 10x19-inch front wheels and 12x20-inch rears that are forged and save 4kg over the standard units.

The elasto-kinematic package has been stiffened at both ends and the front end gets new hub carriers and thicker anti-roll bars, while the steering has also been fiddled.

Mercedes-AMG went for the biggest anchors in the kit bag, with 402mm x 39mm carbon-ceramics up front and 360mm x 32mm rotors on the rear axle. These brakes are also a feature of the SLS Electric Drive, but their set-up is infinitely more complicated than on the Black Series.

What makes the braking complicated is that inboard of each brake rotor is a synchronous electric motor. The SLS Electric Drive has four of them with a combined 552kW of power and 1000Nm of torque. So, that’s even more power than the SLS Black Series and a whole lot more torque.

Each of these motors weighs 45kg and can spin up to 13,000rpm. They drive their wheels through a unique transmission than allows them to drive each wheel as accurately as a hub-mounted motor without the issues of unsprung mass.

These motors not only provide the unbelievably accurate delivery of drive to each tyre, but are in charge of regenerating braking energy as well. The Electric Drive delivers three different stages of brake energy recuperation using lessons learned from the McLaren and Mercedes-Benz F1 teams. On its most aggressive setting, the brakes themselves are barely needed for typical urban work because the electric motors slow the car so effectively.

The 548kg lithium-ion battery pack delivers 600kW of potential performance, thanks to 60kW/hours of energy content. The battery pack itself is liquid cooled (and heated, depending on the climate) and has 12 modules with 72 cells at 400 volts. Technically, it’s three batteries in series, each with four 5kW/hour modules in it.

The battery pack is engineered to last for at least 10 years worth of charging and discharging and can be fully recharged in three hours from a 22-volt wallbox charge station. If that’s not working for you, the AMG mechanics can swap the battery out for a freshly charged one in about half an hour less than a full charge takes.

That’s the main part of the Electric Drive’s mechanicals sorted out. The other areas that have been tweaked include the utter lack of a tailshaft or rear differential but the biggest change has been to the front suspension. The layout of the electric motors meant the upright damper struts were in the way, so they’ve been turfed for a horizontal setup, worked from the suspension via pushrods.

And it’s just over two tonnes, with almost all the difference to the SLS Black Series being made up in battery weight. Or, if you look at it another way, fuel…

In our experience, even that could be accredited to the new Michelin Pilot Sport Cup 2 tyres. It would appear AMG has approached the limits of longitudinal grip for the SLS architecture.

But there is more to the Black Series than a stronger engine and stickier rubber. For starters, it’s louder, thanks to a combination of the exhaust, little interior deadening and carbon-fibre seat shells. Actually, that’s wrong. It’s much louder.

The stock SLS isn’t quiet and isn’t for the shy, but the Black Series opens the door to an entirely new world of anger management. It starts with the traditional snarl of this engine, but adds a metallic rasp across the top of it that sounds like sheets of corrugated iron being rent asunder.

It’s not an easy car to feel immediately comfortable with and even the painted white lines on the exit of the Le Castellet pitlane deliver a demonstrable jolt into the cabin. We only drove it on the track and its management of the (few) bumps there doesn’t auger well for on-road driving.

The reason it feels so initially stand-offish is that it is remarkably difficult to be smooth in the Black Series, especially if you drive it like it wants to be driven. Part of this is down to the tyres, which aren’t efficient until they’re warm and remain efficient only until they reach the upper end of their temperature range. And with the rear tyres warmed up, it’s always the rear-end that lets go first, even in very fast corners.

And it doesn’t like bumps, even the friendlier kind you get on racetracks. With its suspension in ‘Race’ mode, we found it couldn’t track behind a standard SLS over the kerbs on a couple of key corners on the track, then couldn’t tuck its nose into a couple of the tighter ones.

The trick with this car is to drive it with mega aggression. Stay off the kerbs and it will eat metres on a very well driven SLS at every corner, extra distance or not.

It wants you to stand on the brakes hard, then turn it and hammer it hard, again. And it trusts both you and its own skid-control systems to catch the oversteering slides it hits you with, even at 200km/h and in spite of the 50kg of rear downforce the Aero Pack brings with it.

That’s all going to be fine out on the racetrack, but an SLS Black Series on the road? That’s another challenge for another day, but it’s safe to say not many of them will come out in the snow.

AMG says it’s as close as possible to a GT3 car for the road and the performance is certainly hard and fast. But it’s not quite intuitive and not always fluid.

The upshot is that most SLS customers are going to feel more comfortable driving quickly in their own car, even if it’s a touch slower.

That won’t be the same for the Electric Drive, which is just insanely fast everywhere, even if its weight means it won’t stay with a Black Series on a fast track.

But there is more to that story on tight, winding pieces of road not just because of the sheer urge it thumps out from its four electric motors, though that’s a good start. The electric version of the SLS simply takes everything the V8 can do in a corner and moves the game so far forward that the Black Series seems like it’s based on yesterday’s technology.

It’s the addition of intelligent torque dynamics that makes the biggest difference, which isn’t to say the power delivery from the electric motors is worth sneezing at.

The electrified SLS is quick in a straight line, slicing to 100km/h in 3.9 seconds – just two-tenths slower than the standard SLS and three-tenths slower than the Black Series - on its way to a limited top speed of 250km/h (the derestriced Black does 315km/h).

It’s oddly fast, rather than delivering the brutal speed of the SLS Black Series. You step on the throttle and it jumps ahead before settling into a surge that feels like it will never end. All the while Benz’s e-sound (it’s artificial internal-combustion-type sound pumped through the audio system) is trying to convince you that it’s a bit like a petrol-engined car from certain angles. But it does it all too quietly.

The e-SLS stops well, too. You can choose the level of electric regeneration you want to have under braking and chances are that on the top level you’ll barely need to touch the brakes at all. The four electric motors will be so busy harvesting your energy for the lithium-ion batteries that the carbon-ceramics can have a rest.

But the SLS Electric Drive’s real trick is cornering. It’s astonishing. Plenty of cars can brake each wheel with utter precision to maximise the grip available in a corner. This is the only one that can accelerate each wheel with exactly the same precision in exactly the same way. The electric motors are that fast and that accurate with where they put their energy. There is no wasted drive and no cheeky Newtons disappear in tyre smoke.

It takes some familiarisation, but on the track test we had, you could take the SLS and slide it into corners with outrageous enthusiasm, only for the tyres to find bite where physics and years of experience suggested there should be none. Not just bite, but forward drive as well.

It didn’t matter whether it was heaved into fast corners, slow corners, slaloms or chicanes, the Electric Drive allowed a trace of slip on the way in to corners but next to none from the instant you picked up the throttle pedal.

That worked two ways as well. As astonishing as it was to drift an electric car, then fire it out of a corner in a way AMG’s supposed hero, the SLS Black Series, simply couldn’t match, it was more astonishing to flick it into a direction change.

In a slalom or a switchback, the SLS Electric Drive just does things that don’t seem physically possible. It has a full-throttle yaw rate you normally only find in open-wheel racing cars aided by huge downforce.

The only flaw is that the much-vaunted synthesised noise feature isn’t really loud enough or intuitive enough, so it ends up feeling like you’re actually in a passion-less video game, even if you’re being thrown from side to side hard enough to need a karting seat.

But it’s a brilliant piece of engineering, clearly the result of years of passionate work that delivers a game-changing package. The electric SLS is an exciting signpost for the future, but it doesn’t incite as much passion as the Black.

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