Engine will debut in the upcoming 2012 SLK 55 AMG and features a standard output of 310 kW (416 bhp / 422 PS) and 540 Nm of torque.

Mercedes-Benz has announced the new AMG-developed, naturally-aspirated 5.5 liter V8 engine.

The M152 unit produces an output of 310 kW (416 bhp / 422 PS) and 540 Nm (398 lb-ft) of torque and will first be introduced in the upcoming 2012 SLK 55 AMG.

The engine is based on the M157 unit - a 5.5 liter twin-turbo V8 the automaker introduced last year. Both powerplants feature the same displacement (bore/stroke). The M152 represents a 30 percent improvement in fuel-economy over the previous unit and has a consumption rating of 8.5 liters/100 km in the SLK 55 AMG.

That low fuel-economy rating comes by means of a new feature called AMG Cylinder Management - a cylinder shut-off system that can reduce the V8 to a four-cylinder which still sports a healthy 230 Nm (170 lb-ft) of torque.

The 2012 Mercedes-Benz SLK 55 AMG with the new power unit is expected to debut at the Frankfurt motor show in September.

See the press release below for full details on the engine's development.