A method of controlling a vehicle uses a detachable knob. The method includes detecting whether the detachable knob is attached to a first display of an audio video navigation (AVN) system. The first display includes a number of regions. Information on a controlled function corresponding to one of the regions to which the detachable knob is attached is transmitted from the AVN system to the detachable knob. A first user interface corresponding to the information the controlled function is output on a second display of the detachable knob. Result information according to an operation of the detachable knob is transmitted from the detachable knob to the AVN system. The controlled function is controlled based on the result information in the AVN system.