Owners repeatedly single out the hand-built supercharged 5.4L M113K paired with the 722.6 five-speed as the standout W463 drivetrain, calling it the best V8 Mercedes ever made and expecting it to outlast every later G engine with basic maintenance. The supercharger belt is described as trivially easy to service, and the car will limp home even without it.
The M113K supercharged V8 (G55) as the enthusiast-favorite drivetrain
Mercedes-Benz G55/G63 AMG (W463 2004-2018) · mechanical