A navigation system used by a user includes a navigation unit and a portable device. The navigation unit generates navigation-related output. The navigation unit transmits the navigation-related output to the portable device over a wireless communication link. The portable device receives the navigation-related output and uses at least a portion of the navigation-related output for processing performed thereby. In one embodiment, the portable device includes an input interface to receive user input from a user of the portable device. In such an embodiment, the portable device transmits the navigation-related input to the navigation unit over the wireless communication link, and the navigation unit uses at least a portion of the navigation-related input to generate the navigation-related output.