A portable navigation device (PND) is disclosed comprising processing means, a graphical display, memory, map data stored in said memory, user-input means, and signal reception means for receiving one or more wireless signals by means of which the processor can determine a present location of the device and in conjunction with user input desired destination information, and perform route calculation and subsequent navigation functions, such being performed by software installed on the device. The PND is additionally provided with one or more wireless signal transceivers capable of establishing wireless communications with third party devices or systems having corresponding signal transceivers. In accordance with the invention, the software on said PND is adapted to establish a wireless communication with a third party device being a node having a corresponding wireless signal transceiver and being part of a vehicle controller area network (CAN) consisting of a plurality of nodes, each of said nodes having functionality represented by one or more signals distributed around said controller area network and received by at least said third party device, and further characterized in that said PND software includes one or more routines specific to the functionality of one or more of said nodes so as to effectively communicate with said node and utilize its functionality. Examples of third party devices include hands-free communications modules, gateway nodes, and indeed any vehicle subsystem which provides some function within the vehicle. Further examples include the stereo systems, engine management system, seat position controllers, multifunction steering wheel, dashboard and console displays, integrated navigation systems, and the like. The invention allows the PND either to interrogate the controller area network and retrieve information from one or more devices forming nodes on that network for display on the PND or improved operation thereof, or to cause control or state change of one or more of the devices forming nodes on the controller area network. Voice control of the PND is also possible in the case a voice recognition system is provided within the controller area network, and additionally, the vocal instructions issued by the PND can be caused to be replayed through the car stereo, if such is also connected to the controller area network within the vehicle.