First details: Mercedes confirms new Gullwing

MERCEDES-AMG has confirmed it will produce a modern-day successor for the legendary 300SL in 2010, when the original iconic ‘Gullwing’ coupe will be 55 years old.

News of the much-hyped SLS AMG, as it will be called, leaked on the eve of the Geneva motor show last week, when Mercedes-Benz was happy to let the limelight linger on the revised E-class Coupe and Estate.

But now Benz has confirmed the SLS AMG, which will also be a long-anticipated effective replacement for the German luxury giant’s McLaren SLR supercar, which was built in limited numbers by its Formula One partner McLaren and cost more than $1 million in Europe.

The Stuttgart maker’s most formidable in-house sportscar was officially revealed this week via no fewer than 51 images, which show the top-shelf coupe’s overall proportions as it undergoes both hot and cold-weather testing in only light disguise.

Other action shots at both Germany’s Nurburgring and Pikes Peak in the US reveal its long-bonnet links with the outgoing SLR and the iconic road-going version of the gullwing racer Stirling Moss drove to victory in the 1955 Mille Miglia.

But while the full complement of developmental, technical and even part-interior images prove that next year’s AMG super-coupe is all but production-ready, it is the first official “provisional” specifications list that confirms the SLS as the historic maker’s most serious shot yet at the likes of Ferrari, Lamborghini and Porsche.

Heralded as the first vehicle developed entirely in-house in the 40-year history of Mercedes-AMG, the SLS AMG won’t be fully unveiled until the Frankfurt motor show in September.

But its maker has announced its new performance flagship will be powered by a “thoroughly reengineered” dry-sump version of the 6.2-litre AMG V8 that powers everything from the C63, CLK63, E63 and CLS63 to the S63, SL63 and CL63 AMGs – but this time delivering 420kW at 6800rpm and 650Nm of torque from 4750rpm.

That might seem somewhat paltry beside the 460kW and 780Nm offered by the 2003 SLR’s supercharged 5.4-litre aluminium V8, not to mention the 478kW/820Nm version of AMG’s superseded SOHC V8 that powers both the 2006 722 Edition SLR and the swansong SLR Stirling Moss speedster. The latter will be the final SLR variant to be produced after a seven-year production run that will end in December 2009.

But thanks to its all-new aluminium spaceframe body (the first to appear from Mercedes-Benz) that helps keep kerb weight to a still-hefty 1620kg, the SLS hits the scales almost 150kg lighter than the carbon-fibre-bodied SLR (1768kg) it replaces.

Mercedes says the SLS will deliver the best power-to-weight ratio in its class at 2.84kg/hp and, in line with its positioning as an “uncompromising sports car”, claims it has “ideal” front/rear weight distribution at 48/52 per cent.

“Precise steering, first-class agility, low inertia with spontaneous directional changes and outstanding traction” are said to be the result.

While the SLR also featured a front/mid-engined chassis layout, the SLS's 48/52 front/rear weight bias is largely a result of the fact it goes further by adopting a Ferrari-style rear-mounted transaxle, which in this case incorporates a seven-speed dual-clutch automated manual gearbox – another first for Merc.

Simply described as “a new AMG dual-clutch transmission with seven gears”, the BMW M3-style twin-clutch auto, which is driven by a lightweight carbon-fibre driveshaft similar to that in the DTM C-class touring car, has four driving programs plus a launch control system dubbed Racestart.

As with the SLR, a mechanical rear differential lock is fitted to the rear-drive SLS.

Other notable SLS Gullwing features include lightweight forged aluminium double wishbones and wheel hubs all round, ceramic composite brakes, staggered 9.5x19-inch (front) and 11.0x20-inch (rear) light alloy wheels with unique 265/35 R19 (front) and 295/30 R20 (rear) tyres.

There will also be an SL65 Black Series-style three-stage electronic stability control (ESC, or ESP in Benz-speak) system as pioneered by BMW’s M cars.

Many weight-saving measures went into the ballistic Benz’s heavily reworked 6.208-litre “6.3” AMG V8, including a new intake system, revised valve train and camshafts and flow-optimised tubular steel exhaust headers. At the business end, there are high-strength forged pistons and reinforced crankshaft bearings within an “optimised crankcase structure”.

While the dry-sump lubrication system allows the engine to be placed lower in the vehicle, lowering the car’s centre of gravity and improving handling dynamics, its on demand high-performance oil pump also improves lubrication under higher loads.

Despite its higher output and stronger components, the higher-revving and allegedly more responsive AMG V8, which earns the internal codename M159 instead of the “entry-level” engine’s M156 moniker, is also lighter.

At 206kg (the SLR’s similarly hand-built blown V8 weighed 232kg), Mercedes-AMG says the SLS’s naturally-aspirated DOHC V8 possesses “by far” the best power-to-weight ratio among its competitors, at 0.36kg/hp.

And it’s cleaner, as well as lighter and more powerful. Also listed as provisional is the SLS’s combined average European fuel consumption cycle figure of around 13L/100km, thanks in part to AMG’s exclusive friction-reducing twin-wire-arc-sprayed (TWAS) cylinder wall coating, and the on-demand, map-operated oil supply system. Benz says the M159 V8 will meet the EU5, LEV2 and ULEV future emissions standards.

Despite all that, however, judging by its own provisional claimed 0-100km/h figure of 3.8 seconds, AMG’s SLS is no quicker than its McLaren-made predecessor, which had a top speed of 334km/h while the SLS will offer only about 315km/h.

While the limited-edition SLR Stirling Moss is about 200kg lighter than the regular SLR mostly because it has no windows or roof, it comes with a 0-100km/h claim of less than 3.5 seconds, making it narrowly quicker than what the SLR was in the hands of some US testers.

So it seems the SLS will not only fail to match the pace of its similarly sized SLR forebear, but also that of today’s benchmark supercars like Porsche’s turbocharged 911s, Ferrari’s 430 Scuderia and 599 GTB, Lamborghini’s fastest Murcielago and Nissan’s GT-R.

The two-seater SLS AMG, development of which began in late 2006 and will be completed in time for its Frankfurt show debut, will go on sale in Europe next year and in 2010 and should cost about $450,000 by the time it reaches Australia – around mid-way between the CL and SL63 AMG two-doors and the V12-powered CL/SL65 AMGs.

That will make it significantly less expensive than the SLR, which was not sold in Australia, though production is expected to far exceed to the SLR’s build rate, which was originally intended to total 3500 over seven years or 500 annually.

The SLS will be built at Mercedes’ Sindelfingen plant, where Mercedes Technology Centre (MTC) technicians developed it, with pre-assembly taking place at German vehicle specialist Magna Steyr.

A soft-topped convertible version is also under development and is likely to wear an SLC badge when it surfaces in 2012 – the same year Merc’s next-generation SL is due to appear, wearing SLS styling cues and riding on a variation of its all-alloy body and chassis.

“Mercedes-Benz is presenting an exhilarating super sportscar in the guise of the new SLS AMG, which is bound to set the pulses of all car enthusiasts racing that extra bit faster,” said the chairman of Daimler AG and head of Mercedes-Benz Cars, Dr Dieter Zetsche.

“The SLS AMG is emotion pure and simple for the Mercedes-Benz brand and is set to become one of the most alluring sportscars of our era.”