Method for operating a navigation system of a vehicle, comprising the following method steps: - providing one or more dedicated route options for route calculation by the navigation system; - transmitting a first signal to a vehicle-external data processing device for requesting one or more route options provided by the vehicle-external data processing device for route calculation by the vehicle-external data processing device; - receiving a second signal from the vehicle-external data processing device, said second signal identifying one or more route options provided by the vehicle-external data processing device for route calculation; - outputting at least one of the dedicated route options and at least one of the route options identified in the second signal by means of an output unit of the navigation system in order to make it possible for a user to select from those output at least one of the dedicated route options and from those output at least one of the route options identified in the second signal; - detecting at least one input of the user of the navigation system for selecting one of the route options output; - if the selected route option is one of the route options identified in the second signal, transmitting a third signal, which identifies said selected route option, to the vehicle-external data processing device and receiving a fourth signal from the vehicle-external data processing device, said fourth signal identifying a route assigned to the selected route option and calculated by the vehicle-external data processing device; - if the selected route option is one of the dedicated route options, calculating a route assigned to this route option; and - outputting the calculated route by means of the output unit of the navigation system, wherein the navigation system or the vehicle-external data processing device is configured to calculate the route based on a start and destination. - providing one or more dedicated route options for route calculation by the navigation system; - transmitting a first signal to a vehicle-external data processing device for requesting one or more route options provided by the vehicle-external data processing device for route calculation by the vehicle-external data processing device; - receiving a second signal from the vehicle-external data processing device, said second signal identifying one or more route options provided by the vehicle-external data processing device for route calculation; - outputting at least one of the dedicated route options and at least one of the route options identified in the second signal by means of an output unit of the navigation system in order to make it possible for a user to select from those output at least one of the dedicated route options and from those output at least one of the route options identified in the second signal; - detecting at least one input of the user of the navigation system for selecting one of the route options output; - if the selected route option is one of the route options identified in the second signal, transmitting a third signal, which identifies said selected route option, to the vehicle-external data processing device and receiving a fourth signal from the vehicle-external data processing device, said fourth signal identifying a route assigned to the selected route option and calculated by the vehicle-external data processing device; - if the selected route option is one of the dedicated route options, calculating a route assigned to this route option; and - outputting the calculated route by means of the output unit of the navigation system, wherein the navigation system or the vehicle-external data processing device is configured to calculate the route based on a start and destination.