Mercedes CLS550 V8 Bi-Turbo Powerful ECU Tuning VRTuned.com January 14, 2016 Product Info The Mercedes CLS550 M278 engine is huge power plant for the large sporty sedan. The 4.663 liter V8 Bi-Turbo engine produces 402 bhp while matched with a 7 speed automatic transmission. Driving this car...