First look: Benz flips SLS AMG’s wig

MERCEDES-BENZ has released the first official images of its worst-kept secret, the SLS AMG Roadster, which is now confirmed to make its global debut at the Frankfurt motor show on September 13 before first Australian deliveries commence some time in 2012.

The timing confirms the open-top supercar, which does away with the SLS AMG Coupe’s most striking feature – its roof-hinged ‘gullwing’ doors – will be released before the all-electric SLS AMG E-Cell coupe becomes available to order, at least in Europe and the US, in 2013.

Revealed in a range of 14 unflattering images, a partially disguised engineering test mule complete with kitsch red fabric soft-top and black adhesive foil covering its badges shows the convertible version will not feature a folding hard-top like the SL or SLK.

Instead, the Roadster’s headline act is a folding three-piece soft-top that opens or closes at the push of a button in just 11 seconds at speeds of up to 50km/h, matching some of the best convertibles in the business.

Housed behind the seats in a space-saving Z-formation, the soft-top features a rear window made from single-layer safety glass and, says Benz, is free of flapping, booming, hissing, clattering, whistling or howling even at its electronically limited top speed of 317km/h.

Mercedes says the topless SLS, which was developed in tandem with the coupe – AMG’s first independently created model – is based on the same lightweight aluminium spaceframe chassis.

As such, its bodyshell is claimed to weigh just 2kg more than the hard-top’s at 243kg, following the addition of two reinforcements to maintain structural rigidity and improve handling and refinement.

Improving crash performance and negating the need for “additional weight-increasing vibration dampers often employed by competitors” is an additional strut mounting stay between the soft-top and fuel tank, said to increase rear axle stiffness, and extra supporting struts for the dashboard cross-member at the centre tunnel and windscreen frame.

There is also a reinforcing cross-member behind the two front seats to support the fixed rollover protection system and house the 250-Watt subwoofer of AMG’s Bang & Olufsen audio system.

“Without bodyshell rigidity there are no handling dynamics and neither can the close fit of the soft top be guaranteed,” said AMG development director Tobias Moers.

Mercedes-AMG says the 2012 SLS Roadster’s three-year development program focussed on chassis stiffness, driving dynamics, the soft-top and noise, vibration and harshness.

As with all Mercedes roadsters and cabriolets, the new SLS roof was tested 20,000 times on a stationary test rig and 2500 times on the move in all conditions.

Now, a special accelerated endurance trial – including 10,000km at the Nurburgring, 10,000km in city traffic, full-load testing under maximum acceleration and braking, long-term corrosion tests and fully laden work – is attempting to simulate the roof’s performance over the vehicle’s entire life cycle “to verify the level of maturity” before the board approves production of customer vehicles.

Of course, the SLS AMG Roadster is powered by the same 420kW/650Nm dry-sump version of AMG’s soon-to-be-discontinued 6.2-litre V8, rather than the electric motors positioned at each corner of the E-Cell, which delivers total outputs of 392kW and an instantaneous 880Nm.

Mercedes-Benz has not revealed official acceleration figures for the SLS Roadster, but it is expected to all but match the coupe’s 3.8-second 0-100km/h pace – two seconds quicker than the E-Cell.

Australian Mercedes-Benz spokesman David McCarthy confirmed the SLS AMG Roadster would go on sale here next year, but was unsure when or at what price.

However, he said the newest Mercedes convertible would be a full-time model in the local Benz line-up, but a lower than expected price increase over the $468,820 SLS AMG Coupe is still likely to make it Australia’s most expensive Mercedes.

That honour currently goes to the CL65 AMG coupe ($519,250), with the SL65 AMG Roadster not far behind at $513,760, but Mercedes will be keen for the SLS AMG Roadster to remain competitive with exotic convertibles like Porsche’s range-topping 911 Turbo S ($442,800), the Ferrari California ($459,650) and Lamborghini Gallardo ($515,000).

“The SLS Roadster will go on sale here next year, but we don’t know exactly when yet,” said Mr McCarthy.

“We will have a couple of dealer demos and supplies won’t be limited, but like the coupe it will be built to specific customer order.

“There will be a premium, but I don’t expect it to be huge.”