2014 BMW F15 X5 Cruise Control Buttons Guide [Video]
Still, BMW decided to release a video, showing you what the buttons do and how to use them. So, in order to activate the Cruise Control, you have to press the bottom left button on the left side of the steering wheel and then press the "SET" button to maintain or memorize the current speed.
In order to change the speed, you'll have to use the rocker switch located next to the SET and RES buttons. Pressing the rocker switch upwardly will increase the speed by 1 mph (1 km/h in countries that use the metric system) whilst pressing it the other way around will do the opposite.
Pressing rocker switch's buttons past the point of resistance will increase or decrease the speed by 5 mph. In case you came to a halt and then resumed your trip, the "RES" button will resume the cruise control speed to the memorized speed. For more info, check the video below.