A new eight-speed automatic transmission is standard on the 2011 models and replaces a six-speed automatic. The xDrive35i has BMW's new single-turbo 3.0-liter inline six-cylinder (replacing a twin-turbo). Tapping technology normally found in hybrids, the 2011 X6 gets regenerative braking that charges the battery only when the car is braking, coasting or decelerating. BMW says this improves fuel economy up to 3 percent.