See also:

Activating HDC
Press the button; the LED above the button lights up. ...

New 8-speed Automatic Transmission with Steptronic.
On both new gasoline models of the BMW X5, sending the newfound power to the standard xDrive intelligent all-wheel drive system is BMW's new 8-speed automatic transmission with Steptronic control. ...

Maintaining/storing the speed
Press the button. When the system is switched on, the current speed is maintained and stored as the desired speed. It is displayed in the speedometer and briefly displayed in the instrument c ...