DAIMLER AG - The Mercedes-Benz SLK 55 AMG is the most powerful SLK of all time. Its newly developed AMG 5.5-litre naturally aspirated V8 engine with cylinder shut-off system combines ultimate performance with the lowest possible consumption levels. With a maximum output of 310 kW (422 hp) and maximum toque of 540 Newton metres, the SLK 55 AMG outperforms all of its direct competitors. Its fuel consumption of 8.4 litres per 100 kilometres (NEDC combined) and CO2 emissions of 195 grams per kilometre are some 30 percent lower than those of its predecessor. High levels of driving dynamics are ensured thanks to the AMG sports suspension with Direct-Steer system, Torque Vectoring Brakes and 3-stage ESP, as well as the AMG high-performance braking system.
Forming part of the third-generation of the SLK, the new top-of-the range AMG model already demonstrates its individuality even at first glance: distinctive AMG light-alloy wheels, specific AMG bodystyling with AMG spoiler lip and two chrome-plated twin tailpipes at the rear complement the classic roadster proportions, while adding a athletic touch. The expressive design of the SLK 55 AMG is both eye-catching and unmistakable.
The SLK 55 AMG is the perfect embodiment of the new AMG brand claim of "Driving Performance": in the compact high-performance roadster segment, there is nothing to compare to its combination of tangible driving dynamics, superior sportiness, unique high-technology and low fuel consumption.
The SLK 55 AMG accelerates from zero to 100 km/h in 4.6 seconds, and reaches a top speed of 250 km/h (electronically limited).
Key data at a glance:
SLK 55 AMG
Displacement: 5461 cc
Bore x stroke: 98.0 x 90.5 mm
Compression ratio: 12.6 : 1
Output: 310 kW (422 hp) at 6800 rpm
Max. torque: 540 Nm at 4500 rpm
Engine weight (dry): 187 kg
Fuel consumption, NEDC combined: 8.4 l/100 km
CO2 emissions: 195 g/km
Acceleration 0 - 100 km/h: 4.6 s
Top speed: 250 km/h*
* electronically limited
The world's most fuel-efficient V8 engine combines the lowest consumption levels with the superior power delivery and the characteristic sound experience which only a large-displacement eight-cylinder engine can provide.
In line with its "AMG Performance 2015" strategy, with the new V8 engine Mercedes-AMG is meeting its promise to continue to reduce both the fuel consumption and emissions of new models over the next few years – while reaching new heights with the central brand claim of "Driving Performance". At the same time, Mercedes-Benz GmbH is also demonstrating its social responsibility with the M152.
New naturally aspirated eight-cylinder engine closely related to the
V8 biturbo
The new naturally aspirated V8 engine is based on the AMG M157 5.5-litre V8 biturbo engine presented in 2010, which powers the E 63 AMG, CLS 63 AMG, S 63 AMG and CL 63 AMG. Numerous design features are identical, such as the displacement, bore/stroke ratio, distance between cylinders, four-valve-per-cylinder design, ECO start/stop function and direct petrol injection technology. Distinguishing features versus the M157 include the cylinder shut-off system, new intake air ducting, new cylinder heads, the modified valve drive, an adapted oil supply system and an optimised crankcase.
Exclusive combination of advanced technologies
The high-tech M152 powerpack enthralls with a combination of advanced technologies which is unequalled anywhere in the world. No other petrol engine features direct injection at a pressure of 200 bar, spray-guided combustion and piezo injectors, all in conjunction with map-controlled cylinder shut-off, an all-aluminium crankcase with "spectacle" honing, four-valve-per-cylinder design with continuous camshaft adjustment, a high compression ratio of 12.6:1, a ECO start/stop function and generator management – while revving to a maximum speed of over 7000 rpm. All of these measures lead to high degree of efficiency, which is a precondition for high fuel efficiency and low exhaust emissions. Moreover, deciding in favour of a large-displacement, naturally aspirated eight-cylinder unit with cylinder shut-off resolves the conflict of aims between high output/torque delivery and decidedly low fuel consumption levels.
Borrowed from Formula 1: AMG Cylinder Management cylinder shut-off system
It is the AMG Cylinder Management cylinder shut-off system in particular – newly developed by Mercedes-AMG - that significantly improves efficiency: cylinders two, three, five and eight are shut off under partial load, which lowers fuel consumption considerably. In similar form this technology is also used in the approx. 750 hp V8 engines found in Formula 1. As efficiency also plays a major role at the pinnacle of motor racing, four or six cylinders are disabled by shutting off the fuel injection when the driver has lower load demands, e.g. when cornering at slow speed, in the Safety Car phases or for pit stops.
Plus the M152 goes even further: the intake and outlet valves also remain closed which results in an additional increase in efficiency. With a fuel consumption of 8.4 litres and CO2 emissions of 195 grams per kilometre (NEDC combined), the naturally-aspirated AMG V8 engine ranks at the same level as its competitors, however these are unable to match either the output or torque of the SLK 55 AMG – and above all, they do not use large-displacement eight-cylinder engines.
The cylinder shut-off function is available over a wide engine speed range from 800 to 3600 rpm if the driver has selected transmission mode "C" - Controlled Efficiency. No less than 230 Nm of torque is still available in four-cylinder mode – enough power to ensure plenty of acceleration in most driving situations. As soon as the driver has a need for more power and leaves the partial load range, cylinders two, three, five and eight are activated. The switch from four to eight-cylinder operation is immediate and imperceptible, leading to no loss of occupant comfort whatsoever. At an engine speed of 3600 rpm the activation process takes no more than 30 milliseconds.
ECO start/stop function as standard
The ECO start/stop function further contributes to the low fuel consumption levels. This system is standard equipment on the SLK 55 AMG, and active in the fuel economy transmission mode Controlled Efficiency "C". Once the driver comes to a halt, the V8 engine is automatically switched off. Once the brake pedal is released or the accelerator is depressed, the engine is immediately restarted and the car is able to move off quickly. A framed "ECO" symbol in the AMG main menu shows the driver that the ECO start/stop function is active. When cylinder shut-off is active, the driver is informed by the symbol "ECO4", while "ECO8" stands for eight-cylinder operation. In the two more performance-oriented driving modes "S" (Sport) and "M" (Manual), the ECO start/stop function and cylinder shut-off system are deactivated. If required, the driver can also switch the systems off while in "C" mode. In this case neither a "start/stop" nor an "ECO" symbol appears. A generator management system makes a further contribution to fuel economy: whenever the V8 engine is on the overrun or when braking, kinetic energy is used to charge the battery rather than being wasted as heat in the usual way.
New AMG sports exhaust system with integrated exhaust flaps
For the first time AMG is using a sports exhaust system featuring an exhaust flap on each side. This technology resolves the conflict of aims between an emotional sound when driving in a sporty manner and a more discreet engine note in the partial load range. The main focus of the sound design was on achieving a perfect synthesis of perceptible dynamism and the long-distance comfort that is a hallmark of Mercedes.
Each of the two rear silencers has a flap which is variably activated on a logic-controlled basis, depending on the driver's power requirement and the engine speed. The two-pipe AMG sports exhaust system with two chromed twin tailpipes has a pipe diameter of 65 millimetres from the manifolds to the pre-silencer. The diameter is reduced to 60 millimetres from the pre-silencer to the rear silencers. Low exhaust emissions, compliance with all country-specific standards and a characteristic engine sound – the requirements for the exhaust system of the naturally aspirated AMG 5.5-litre V8 engine were manifold and complex. The SLK 55 AMG complies with the current Euro 5 emission standard, as well as meeting all of the requirements of the US market (LEV III standard, On-Board Diagnosis II).
Highly variable: the AMG SPEEDSHIFT PLUS 7G-TRONIC
Power is transferred to the rear wheels by means of the AMG SPEEDSHIFT PLUS 7G-‑TRONIC automatic transmission which features three transmission modes: Controlled Efficiency (C), Sport (S) and Manual (M). The automatic double-declutching function when downshifting as well as the brief, precisely defined interruption of ignition and injection when shifting up under full load shorten shifting times and increase emotional appeal when adopting a sporty driving style. A double turbine torsional damper with centrifugal pendulum which adapts to engine speed helps to minimise vibrations in four-cylinder operation mode and enhances the impression of comfort experienced by the vehicle occupants.
Perfect combination: highly dynamic driving style and comfortable cruising
The AMG sports suspension with Torque Vectoring Brakes and AMG Direct-Steer system provides both impressive lateral dynamics as well as agile handling, together with the comfort on long journeys which is characteristic of a Mercedes. Looking for a highly dynamic driving style or comfortable cruising? The new SLK 55 AMG is able to offer both. Independent suspension struts with stiffer spring/damper tuning, torque strut bearings on the front axle featuring higher rigidity, stiffer stabilisers all round as well as a more negative camber on the rear axle result in high cornering speeds and a low body roll in fast S-shaped bends.
In critical cornering conditions, the Torque Vectoring Brakes produce a defined rotational movement of the vehicle about the vertical axis in fractions of seconds, through selective brake actuation at the rear wheel on the inside of the bend. This results in the SLK 55 AMG steering into the bend precisely and under full control, without any compromises where dynamism is concerned. Complementing this feature perfectly is the AMG Direct-Steer system: it enhances handling and agility compared with the standard steering, whilst also reducing the amount of physical effort required when parking. A new power steering pump helps to reduce fuel consumption. The power assistance for the steering only requires energy when the driver is actually steering. In addition, the AMG Direct-Steer system has a parameter function adapted to match the characteristics of the AMG sports suspension. This results in optimum response from the central position, outstanding road feel and dynamic handling in all driving situations.
The AMG-exclusive 3-stage ESP gives three individual control strategies at the touch of a button: the ESP button in the centre console allows the driver to choose between "ESP ON", "SPORT Handling Mode" and "ESP OFF". The AMG high-performance brake system is characterised by outstanding responsiveness, short stopping distances and excellent fatigue strength.
Optional AMG Handling package for even greater driving dynamics
The optionally available AMG Handling package enhances the vehicle's sportiness even further. It comprises an AMG Performance suspension with stiffer tuning, an AMG rear axle differential lock, composite brake discs at the front and a three-spoke AMG Performance steering wheel finished in nappa leather with Alcantara inserts in the grip areas.
Unmistakable: uniquely styled design and appointments
Classic roadster proportions with typical AMG design characteristics as well as a hint of the SLS AMG – these are the striking visual highlights of the new SLK 55 AMG. The AMG designers have complemented the exciting basic forms of the long bonnet, the greenhouse positioned well to the rear and crisp rear section with characteristic AMG styling at the front, sides and rear. The new AMG front apron has large air inlets and AMG-specific LED‑daytime driving lights. Inspired by the SLS AMG super sports car, the wide radiator grille features a large, centrally-positioned Mercedes star. In the case of the SLK 55 AMG, the slats in the radiator grille and the lower cross strut on the front apron are painted in a high-gloss black finish. Headlamps with darkened edging and darkened bicolour tail lamps also come as standard exclusively on the top-of-the-range V8 model. The Intelligent Light System (ILS) is also available as an optional extra.
The vent grilles with chrome-plated fins in the front wings are not only reminiscent of the SLS AMG, but also evoke memories of the famous Mercedes-Benz 300 SL Roadster from the 1950s. The "V8 AMG" lettering beneath the grilles points to the top-of-the-range eight-cylinder model from the SLK model series. AMG-specific, distinctively styled side sill panels continue the design of the front apron through to the new rear apron. With its own unique shape, black diffuser insert with three fins as well as the two chrome-plated twin tailpipes of the AMG sports exhaust system, it gives a striking finishing touch to the vehicle. The spoiler lip on the boot lid, painted in the vehicle body colour, reduces lift at the rear axle and thereby increases driving stability at high speeds.
Inspired by the SLS AMG: high-quality, stylish interior
Functional, stylish, high-quality: the interior design of the SLK 55 AMG is also reminiscent of its bigger brother, the SLS AMG Roadster. Associations with the super sports car are evoked courtesy of the four air vents in the style of jet engines, as well as the centre console finished in brushed aluminium. An optional addition to the centre of the dashboard is an AMG-specific analogue clock featuring an IWC design. The AMG Performance steering wheel, with its flattened top and bottom sections, also boasts metal trim, aluminium shift paddles and grip areas finished in perforated leather. The clearly-arranged AMG instrument cluster is positioned perfectly in the driver's field of vision and features two circular instruments, distinctive dials and the AMG main menu. The switch for the transmission modes C, S and M is also located in the centre console.
The AMG sports seats with individual seat upholstery layout come as standard with the upholstery combination ARTICO man-made leather/black fabric and high-quality AMG badges in the backrests. Sun-reflective nappa leather and Exclusive nappa leather are both available as optional extras.
Exceptional position: modern assistance systems on board
The SLK 55 AMG sets new standards when it comes to safety: a whole host of the latest assistance systems support the driver and have helped to secure the new AMG Roadster's exceptional position in its segment. Standard equipment includes new, fibre-reinforced roll-over bar, two-stage driver and front passenger airbags, headbags, thorax airbags, seat belt tensioner with degressive belt force limiters, NECK-PRO crash-active head restraints, automatic child seat recognition, three-stage ESP and also ATTENTION ASSIST drowsiness detection. Further assistance systems are available on request: DISTRONIC PLUS, the Intelligent Light System (ILS), Speed Limit Assist, the anticipatory occupant protection system PRE-SAFE and the PRE-SAFE Brake.
Three generations: the SLK made by AMG
The new SLK 55 AMG is already the third generation of the exclusively dynamic roadster model made by AMG. It all started in 2001 with the SLK 32 AMG. Its AMG V6 supercharged engine with a displacement of 3.2 litres produced 260 kW (354 hp) and maximum torque of 450 Nm – as such, the SLK 32 AMG was the most powerful vehicle in its class.
At the end of 2004 this was followed by the SLK 55 AMG. With its AMG 5.5-litre V8 engine, which developed 265 kW (360 hp) and 510 Nm of torque, it also assumed the leading position in its segment. No other vehicle in this class offered a large-displacement eight-cylinder engine – and Mercedes-AMG has remained consistently true to this philosophy with the successor model. The new SLK 55 AMG will celebrate its market launch in January 2012.