The SLS AMG Roadster: open-top sensuality(en)

../../JPG/AMG/AMG00087.jpg, photo by daimler 2009

AMG, the high-performance brand within Mercedes-Benz Cars, is presenting a new dream car: the SLS AMG Roadster. Two years after the sensational launch of the gullwing model at the 2009 International Motor Show (IAA), the open-top variant of this super sports car is now set to follow. The technological highlights of the SLS AMG Roadster read like an A-B-C of modern sports car engineering: the combination of an aluminium spaceframe body, an AMG 6.3-litre V8 front-mid engine with dry sump lubrication developing a peak output of 420 kW (571 hp) and 650 newton metres of torque, a seven-speed dual clutch transmission in a transaxle arrangement and a sports suspension with aluminium double wishbones is guaranteed to make the hearts of sports car enthusiasts beat faster – while ensuring outstanding driving dynamics and roadster motoring pleasure. The compact fabric soft top of the SLS AMG Roadster opens and closes in just eleven seconds, and can be operated on the move at speeds up to 50 km/h. The new AMG RIDE CONTROL sports suspension with electronically controlled damping is available as an attractive optional extra. It enables the damping characteristics to be modified at the touch of a button. Using the AMG DRIVE UNIT, the driver of the SLS AMG Roadster is therefore able to choose his own suspension setup. Three modes are available: "Comfort", "Sport" and "Sport plus"."AMG Performance Media" is a unique new feature: this innovative multimedia system inspired by motorsport offers an unrivalled combination of numerous telemetric displays such as lateral and linear acceleration, various engine data and lap times on a racetrack, and also features high-speed mobile internet access. Dr Dieter Zetsche, Chairman of the Board of Management of Daimler AG and CEO of Mercedes-Benz Cars: "The SLS Roadster is a super sports car, cruiser and highly desirable dream-car all in one. It its distinctive way, it continues the succession of iconic and exciting sports cars from Mercedes-Benz."Olaf Källenius, Chairman of Mercedes-AMG GmbH: "Systematic lightweight construction, outstanding performance and a breathtaking design combined with sensuous open-air driving pleasure – the new SLS AMG Roadster perfectly embodies the AMG philosophy of German engineering and craftsmanship. The gullwing model has already thrilled sports car fans all over the world, and now the open-top version is bound to cause a sensation."

The new Roadster adds a second exciting dream car to the AMG model family. Head of Design at Mercedes-Benz, Gorden Wagener: "As in the gullwing model, the purist, athletic design immediately captures the attention. Whether with the roof open or closed, the SLS AMG Roadster is an impressive visual delight!" The perfect proportions are particularly memorable: a long bonnet, the greenhouse positioned well to the rear and a short rear end. Plus the automatically extending rear aerofoil, long wheelbase, wide track and short overhangs – in short, the open-top SLS AMG likewise exudes effortless dynamism and an authentic charisma. The pronounced shoulder sections are reminiscent of tensed muscles, and suggest sheer power in combination with the large wheels in size 265/35 ZR 19 (front) and 295/30 ZR 20 (rear). The attractive metallic paint finish AMG Sepang brown and weight-optimised forged wheels in a 10-spoke design, painted in matt black with a high-sheen rim flange, are available as new optional extras.Features reminiscent of the 300 SL Roadster, the classic dream-car from the 1950s, include not only the wide radiator grille with its large Mercedes star and the wing-shaped cross-fin, but also the fins on the bonnet and on the vehicle flanks. Like the SLS AMG Roadster, the 300 SL Roadster appeared slightly later than the original gullwing 300 SL, but unlike in the former case both AMG dream cars are available at the same time.

Interior continues the breathtaking design idiom of the exterior, and awakens associations with an aircraft cockpit: prominent stylistic features include the dashboard in the shape of a wing section and the air vents with adjustable, cruciform nozzles reminiscent of jet engines. The extended centre console of matt, solid metal and the new E-SELECT lever in the shape of an aircraft's thrust control are also design features adopted from the world of aviation. Another discreet, fine detail is the embossed AMG emblem on the leather-lined selector lever. The AMG DRIVE UNIT - which like numerous other interior features is available in real carbon-fibre - is the central control unit in the centre console: it allows the driver to choose a personal vehicle setup, including adjustment of the AMG RIDE CONTROL sports suspension (optional). The AMG Performance steering wheel with its high-grade nappa leather lining and flattened lower rim section allows perfect vehicle control. The shift paddles and lower steering wheel bezel are of solid metal.

The sensual experience in the SLS AMG Roadster is enhanced further when the soft top is open, and the powerful, naturally aspirated eight-cylinder engine with 420 kW (571 hp) and 650 newton metres of torque asserts itself and makes the heart beat faster with its typical AMG eight-cylinder sound. The fabric soft top can be opened and closed while on the move at up to 50 km/h; the fully automatic opening/closing process takes only eleven seconds. The driver only needs to operate the roof control unit conveniently integrated at the front of the centre armrest. When open, the soft top is space-savingly deposited behind the seats in a folded Z-configuration. Three soft top colours - black, red and beige - are available to suit the nine exterior and six interior colours. The three-layered fabric soft top is a weight-optimised magnesium /steel/ aluminium construction, and contributes greatly to the car's low centre of gravity. The soft top has a seamlessly bonded rear window of heated single-layer safety glass ../../JPG/AMG/AMG00087.jpg, photo by daimler 2009

The flush, gap-free transition between the outer roof skin and the rear window keeps wind noise at a low level. A continuous, flexible water pocket running under the soft top catches rainwater and directs it to the underbody via two apertures on each side. The boot capacity is 173 litres with the roof either open or closed, and therefore roughly equal to that of the SLS AMG Coupé (176 litres).

The finest leather, matt-finished solid metal or optional, real carbon-fibre trim create an exclusive ambience and correspond with the authentic feel of the cockpit. Precisely executed decorative and contrasting stitching enhances the visual impression, heightens the hand-crafted look and reflects the attention to detail which is the hallmark of Mercedes design.The standard appointments of the SLS AMG Roadster include black designo leather, AMG sports seats with heating, a slot-in draught-stop, COMAND APS with DVD player, anti-theft alarm system with tow-away protection and interior monitoring, THERMOTRONIC luxury automatic climate control and the KEYLESS-GO starting function. The optionally available AIRSCARF^® system exclusive to Mercedes-Benz acts like an invisible scarf warming the head and neck areas of the occupants. It is integrated into the backrests of the AMG sports seats, and blows warm air from vents in the head restraints. Leather-lined roll-over bars with integrated mesh are available in conjunction with the optional designo Exclusive leather to reduce turbulence in the cockpit. Ambient lighting is integrated into the optionally available, electrically folding exterior mirrors.Single-tone or two-tone designo leather in espresso brown is available as a new interior colour – this dark shade of brown perfectly matches the new metallic paint finish AMG Sepang brown.

Another optional highlight is available in addition to the Bang & Olufsen BeoSound AMG surround sound system, which provides exclusive musical enjoyment at the highest level: Performance Media. In an unprecedented way, this system inspired by motor racing combines numerous telemetric displays such as engine data, lateral and linear acceleration and lap times on a racetrack, as well as providing high-speed mobile internet access. AMG Performance Media is activated by pressing the AMG key in the AMG DRIVE UNIT, and operated using the COMAND Controller. Key functions at a glance:

AMG Performance Media also provides high-speed mobile internet access: when the car is stationary, the driver and passenger are able to surf the web, download and install apps, and send or receive emails – this unrivalled system has functions comparable to those of a PC, notebook or smartphone. AMG Performance Media uses the widespread, high-performance Android operating system. This exclusive new development will also be installed in other AMG high-performance cars in the future.

In addition to a high level of occupant comfort, the key factor for driving pleasure in the new SLS AMG Roadster is of course the outstanding performance. The basis for this is the innovative body design: the chassis and body are of aluminium, a design combining intelligent lightweight construction with high strength. With a DIN kerb weight of 1660 kilograms, the Roadster is only 40 kilograms heavier than the Coupé. The result is a remarkable power-to-weight ratio of 2.9 kilograms per hp. In order to achieve handling dynamics identical to those of the Coupé, despite the lack of a fixed roof, the SLS AMG Roadster has features specifically designed to rigidify the bodyshell, for example side skirts with greater wall thicknesses and more chambers. The dashboard cross-member is supported against the windscreen frame and centre tunnel by additional struts, and a curved strut between the soft top and the tank reinforces the rear axle. To maintain stability despite the omission of the Coupé roof and gullwing doors, the open-top SLS AMG has a reinforcing cross-member behind the seats to support the fixed roll-over protection system. This also accommodates the 250 watt subwoofer of the optional Bang & Olufsen BeoSound AMG high-end sound system. All this prevents unwanted vibrations right from the start, and makes it unnecessary to use the additional, weight-increasing vibration dampers that are often found in open-top sports cars. The weight-optimised aluminium spaceframe weighs 243 kilograms, tipping the scales at just two kilograms more than the gullwing model.

50 percent of the intelligently designed, weight-optimised aluminium spaceframe is of aluminium sections, 26 percent of sheet aluminium, 18 percent of cast aluminium and 6 percent of steel. For maximum occupant safety, ultra-high-strength, heat-formed steel is used in the A-pillars. The entire vehicle concept has been designed to achieve the lowest possible centre of gravity. This applies both to the low connection of the powertrain and axles, as well as to the arrangement of the rigidity-conducive bodyshell structure, which has been kept as low as possible. Examples include the rigid flexural and torsional connections between the front and rear section and the safety passenger cell, which have been realised consistently using force paths that are as low as possible. This results not only in a low centre of gravity but also in a harmonious and therefore efficient force path in the vehicle structure.

The aluminium spaceframe provides the basis for outstanding passive safety. The extensive safety features include the fixed roll-over protection system, three-point seat belts with belt tensioners and belt force limiters, and eight airbags: adaptive front airbags and kneebags, two seat-integrated sidebags and two windowbags deploying from the door beltlines. The optionally available Blind Spot Assist helps the driver with a visual warning symbol and acoustic alert if the danger of a collision with another vehicle is detected when changing lanes.

The SLS AMG Roadster has the same, muscular engine as the gullwing model. The 6.3-litre V8 with a peak output of 420 kW (571 hp) at 6800 rpm makes the open-top SLS one of the most powerful sports cars in its segment. Its power-to-weight ratio is 2.9 kg/hp. This naturally aspirated engine generates its maximum torque of 650 newton metres at 4750 rpm. The open-top SLS AMG accelerates from zero to 100 km/h in 3.8 seconds, reaches 200 km/h in 11.3 seconds and has a top speed of 317 km/h (electronically limited) – which means that the Roadster has a performance comparable to the gullwing variant. The high-revving V8 engine with a cubic capacity of 6208 cc has the typical characteristics of powerful racing engines. It responds immediately to accelerator movements and is extraordinarily willing. The use of a dry sump lubrication system makes for a considerably lower installed position in the vehicle. The resulting, lower centre of gravity allows high lateral acceleration and ensures thrilling driving dynamics.

Despite its uncompromisingly sporty character, very ambitious fuel consumption targets have been met. Like the gullwing variant, the SLS AMG Roadster consumes 13.2 litres per 100 kilometres (NEDC combined), corresponding to CO₂ emissions of 308 grams per kilometre. Efficiency-enhancing measures include the familiar AMG-exclusive, friction-optimised NANOSLIDE coating on the cylinder walls as well as the on-demand, map-optimised oil supply and intelligent generator management: during the engine's overrun phases, kinetic energy is used to charge the battery rather than being wasted by simply generating heat. Conversely, the generator is switched to no-load operation during acceleration, thus reducing the load on the engine. Sophisticated catalytic converter technology enables current and future emission standards such as Euro-5, LEV 2 and ULEV to be met.

The AMG 6.3-litre V8 engine delivers its abundant power to the rear axle via an ultra-light carbon-fibre driveshaft – similar to the setup used in the DTM C-Class racing touring car. The dual clutch transmission is mounted at the rear (transaxle principle), and connected to the engine housing via a torque tube. A carbon-fibre shaft rotates at engine speed in the torque tube. The advantages of this sophisticated solution lie in the rigid link between the engine and transmission and, in turn, the optimum support for the forces and torque generated. The AMG SPEEDSHIFT DCT 7-speed sports transmission boasts fast gear changes with no loss of tractive force – in as little as 100 milliseconds. The driver has a choice of four different driving modes: "C" (Controlled Efficiency), "S" (Sport), "S+" (Sport plus) or "M" (Manual). In the Sport, Sport plus and Manual modes the automatic double-declutching function is active; all the modes can be selected conveniently via the rotary control in the AMG DRIVE UNIT. The RACE START function provides optimum traction -- as does the mechanical differential lock, which is integrated into the compact transmission housing.

The chosen solution with a front-mid-engine plus transaxle configuration ensures an ideal front/rear weight distribution of 47 to 53 percent. Mounting the engine behind the front axle has created the ideal conditions for consummate driving dynamics with precise steering, first-class agility, low inertia with spontaneous directional changes and outstanding traction. All four wheels are located on double wishbones with a track rod, a technology that has proven itself in motor racing right through to Formula 1. With a double-wishbone axle, the wheel location and suspension functions remain separate; the spring/damper struts are supported on the lower wishbone. The double-wishbone concept with its high camber and track rigidity positively locates the wheel with minimal elastic movements, providing the driver with an optimum of road contact when driving at the limits. Wishbones, steering knuckles and hub carriers at the front and rear are made entirely from forged aluminium – substantially reducing the unsprung masses; this configuration also notably improves the suspension response. The long wheelbase of 2680 millimetres not only results in outstanding straight-line stability but also low wheel load shifts, significantly reducing the vehicle's tendency to dive and squat when braking and accelerating. The broad track width – front 1682, rear 1653 millimetres – ensures lower shifts in the wheel loads from the inner to the outer wheel when cornering, enabling the tyres to retain more grip.

The new AMG RIDE CONTROL sports suspension with electronically controlled damping is available as an attractive optional alternative to the AMG sports suspension. It enables the damping characteristics to be modified at the touch of a button. Using a button in the AMG DRIVE UNIT, the driver of the SLS AMG Roadster is therefore able to choose his own suspension and transmission setup. Three modes are available: "Comfort", "Sport" and "Sport plus". The current mode is shown in the instrument cluster. "Comfort" delivers a sensitive response with soft damping characteristics, while in "Sport" mode the shock absorbers have a much stiffer response depending on the driving situation. This not leads to better road contact, but also effectively suppresses body roll and pitching. "Sport plus" is ideal for challenging laps on a racetrack: in addition to the higher damping force, this mode comes with specific control algorithms that have been tailor-made for a decidedly sporty driving style on level road surfaces. The new, variable suspension will also be optionally available for the SLS AMG Coupé in future.

The rack-and-pinion steering gear provides a consistently direct steering feel with a constant mechanical ratio of 13.6:1, in tune with the high expectations placed on a super sports car. The power steering provides speed-sensitive assistance and improves feedback for the driver as the road speed increases: an indispensable factor for high-speed straight-line driving. Mounting the steering gear in front of the engine on the integral subframe enables the engine to be set down very low. The SLS AMG comes with 3-stage ESP^® as standard, providing the driver with access to the three "ESP ON", "SPORT Handling Mode" and "ESP OFF" modes at the touch of a button. In "ESP OFF" mode too, operating the brake pedal restores all the normal ESP^® functions. The acceleration skid control (ASR) system's traction logic is active in all three ESP^® modes. If one of the drive wheels starts to spin, specific brake pressure is applied to improve traction significantly – especially in conjunction with the standard-fit mechanical multi-disc limited-slip differential. This means that the engine power is transferred to the road even more effectively when driving in a particularly dynamic style.

The AMG high-performance braking system with composite brake discs at the front ensures extremely short stopping distances even under enormous loads. From now on, red-painted brake callipers all-round are available on request. The newly developed, optional ceramic composite brakes with even larger brake discs guarantee even better braking performance. The ceramic brake discs perform reliably at even higher operating temperatures thanks to their greater hardness, all combined with an impressive weight reduction of around 40 percent. Reducing the unsprung masses has further improved both comfort and grip, and the reduced rotating masses at the front axle ensure a more direct steering response. Lightweight construction was also key when it came to the wheels: AMG light‑alloy wheels based on the innovative flow-forming principle reduce the unsprung masses while improving driving dynamics and suspension comfort. In addition to the standard-fit AMG 7-spoke light-alloy wheels, 5-twin-spoke wheels and weight-optimised 10-spoke forged wheels are available as an option. 265/35 R 19 (front) and 295/30 R 20 (rear) tyres developed exclusively for the SLS AMG ensure optimum performance. A tyre pressure monitoring system is fitted as standard to permanently monitor tyre pressure in all four wheels, with an individual display for each tyre.

The SLS AMG Roadster was designed and developed in parallel with the Coupé under the autonomous aegis of Mercedes-AMG GmbH. The open-top super sports car will be produced at the largest Mercedes-Benz production plant in Sindelfingen. The AMG 6.3-litre V8 engine comes directly from the AMG engine workshop in Affalterbach, where it ishand-assembled according to the traditional "One man, one engine" philosophy. The market launch of the Mercedes-Benz SLS AMG Roadster will start in October 2011. The purchase price is € 195,160 (incl. 19% VAT).