The basics are this: replacing the previous 5.5-liter V8 and 7-speed auto is an electrically boosted, twin-turbo 4.0-liter V8 generating 603 horsepower and 627 pound-feet of torque. A new 48-volt electrical system can provide additional juice through a motor integrated between the engine and the transmission in what Mercedes refers to as EQ boost; a mild-hybrid technology. The 9-speed twin-clutch gearbox routes power through a fully variable all-wheel drive system …