Abstract: A vehicle includes a navigation device in which a road network, which can be travelled on, has stored therein associated data on the surroundings. The navigation device determines the position of the vehicle on the road network. The stored data on the road network surroundings includes at least data on covered road-network areas, such as tunnels and the like. The navigation device detects when the vehicle is about to travel through a covered road network area and signals this to a control unit which, in response, activates a tunnel-mode function. In the tunnel mode function, the control unit actuates certain vehicle components in a prescribable manner, in order, for example, to switch on the external vehicle lights, close the vehicle openings, switch the vehicle air-conditioning system to air recirculation mode, interrupt interior ventilation and/or switch a vehicle audio system to recorded-medium mode.