- Characteristically AMG: maximum performance, minimum consumption levels
- Groundbreaking: eight cylinder engine with cylinder shut-off system
- Efficient: fuel consumption reduced by 30 percent
- Agile: Direct-Steer system and Torque Vectoring Brake
- Appealing: dynamic design and high-quality appointments
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 Nm (398 lb-ft), the SLK 55 AMG outperforms all of its direct competitors. Its fuel consumption of 8.4 l/100 km (28.00 mpg/US, 11.90 km/l) (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 (62 mph) in 4.6 seconds, and reaches a top speed of 250 km/h/155 mph (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.
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.
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.
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 l/100 km (28.00 mpg/US, 11.90 km/l) and CO2emissions of 195 grams per kilometre (NEDC combined), the naturally-aspirated AMG V8 engine ranks at the same the 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 (170 lb-ft) 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.
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.