A vehicle is equipped with a digital audio broadcast (DAB) receiver 102 and a global positioning system (GPS) receiver 104. The DAB receiver 102 receives a signal which comprises data constituting information relating to terrain, such as road surface conditions, location of bends, gradients, or relating to traffic information, or local speed limits. A processing means 200 uses the GPS data to determine vehicle location, and then extracts the relevant information from the DAB signal. This can then be used either to alert the driver to local speed limits, or to present local traffic information, or to control one or more vehicle functions, such as a cruise control system, traction control, an automatic gearbox, a suspension damping control system or ride height control system. The DAB receiver can also be used to receive software updates for the navigation system or for a vehicle management system 204.