2012 SLK55 AMG to Make More Power, 30 Percent Better Mileage

By Jason Davis | July 21, 2011
Want to have your cake and eat it inside an SLK55 AMG roadster? Mercedes-AMG is helping to make the philosophical conundrum a reality with its newest V-8 for the 2012 SLK55 AMG roadster. We had no issue with the output from the previous model's 355 horsepower, 5.5-liter V-8, but its 14 mpg city and 22 mpg highway mileage ratings were notably lower than BMW's similarly performing Z4. This morning, however, AMG announced the all-new 2012 SLK55 AMG not only sees power increase to 415 hp, but that it also achieves "about 30 percent better fuel mileage."
"Thanks to the innovative AMG Cylinder Management system and other high-tech components, our newly developed AMG M152 naturally aspirated eight-cylinder engine achieves the fuel economy of a four-cylinder with the muscular power delivery and emotional sound experience of a V8," says Friedrich Eichler, head of powertrain development at Mercedes-AMG GmbH. Though AMG did not release EPA numbers, doing the math suggests the new V-8 could see close to 18 mpg in the city and 28 mpg highway mileage, numbers that are now comfortably higher than the Z4. The news comes on the heels of Motor Trend's August 2011 issue where AMG's Managing Director, Ola Kaellenius, was asked about the "future of speed." "Clearly, in the engine/transmission combination, the power delivery [is important] as is efficiency. Our goal is to not only have benchmark performance, but also benchmark efficiency in the segment." In addition to improved breathing and an advanced fuel injection system, AMG also gave the 2012 SLK55 AMG active cylinder management. When cruising on the highway, or at a steady engine speed, the V-8's engine management computer shuts off four of its eight cylinders. This means less fuel gets burned, and if you need extra power to pass a minivan on the highway, AMG promises instantaneous reactivation of the idle cylinders. "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 3,600 rpm the activation process takes no longer than 30 milliseconds." Look for the 2012 SLK55 AMG to debut at the International Motor Show in Frankfurt/Main in September. Source: Mercedes-AMG