2012 Mercedes-Benz SLK 55 AMG

The Mercedes-Benz SLK 55 AMG is the most powerful SLK ever. Its new AMG 5.5-liter V8 features cylinder shut-off to combine the ultimate performance with the best possible fuel consumption.

With a peak output of 422hp and maximum torque of 400 lb-ft, the SLK 55 AMG outperforms its direct competitors. Its fuel consumption of 28mpg US on the European combined cycle and CO2 emissions of 195g/km are around a 30 percent improvement of that of its predecessor.

Forming part of the third-generation of the SLK launched earlier this year, the new flagship AMG model demonstrates its individuality at first glance: distinctive AMG wheels, specific AMG bodystyling and two chrome-plated twin tailpipes at the rear complement the classic roadster proportions.

The SLK 55 AMG accelerates from 0-62mph in 4.6 seconds, and reaches
a top speed of 155 mph

In line with its "AMG Performance 2015" strategy, with the new V8 is meeting its promise to continue to reduce both the fuel consumption and emissions of new models over the next few years with the M152.

The new M152 is based on the AMG M157 5.5-liter 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, distance between cylinders, start/stop system and direct petrol injection technology. Distinguishing features versus the M157 include the new intake air ducting, new cylinder heads, modified valve drive, an adapted oil supply system and optimized crankcase.

It is the AMG Cylinder Management cylinder shut-off system in particular that significantly improves efficiency: cylinders two, three, five and eight are cut off under partial load, which lowers fuel consumption considerably. This technology is similar to that used on the 750hp V8 engines in Formula 1. As efficiency also plays a major role at the pinnacle of motor racing, two or four of the eight cylinders are cut off when cornering at slow speed, in the Safety Car phases or for pit stops.

The cylinder shut-off function is available over a wide engine speed range from 800 to 3600rpm if the driver has selected transmission mode "C" – Controlled Efficiency.

The AMG main menu in the instrument cluster informs the driver whether cylinder shut-off is active, and whether the engine is currently running in four or eight-cylinder mode. 170 lb-ft of torque is still available in four-cylinder mode – enough to ensure plenty of acceleration for 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-cylinders is immediate and imperceptible. At an engine speed of 3600rpm, the activation process takes
no more than 30 milliseconds.
The crankcase of the new AMG 5.5-liter V8 engine features a diecast all-aluminum construction. The low (dry) engine weight of just 412 lb is the result of uncompromising lightweight construction methods. The bearing covers for the main crankshaft bearings are of grey cast iron, and are bolted
to the crankcase, as well as on the sides, for high rigidity.