Navigation system for a vehicle and method of route searching

A navigation system (1) adapted to be installed in a vehicle and including route guidance function comprises a storing unit (22) for storing vehicle emission information (40) which is indicative of an emission characteristic of the vehicle, and a route processing unit (21) adapted for calculating a route (51) to a destination, wherein the route processing unit (21) is adapted for processing the vehicle emission information (40) and for calculating a route (51) to a destination depending on the vehicle emission information. In this way, route calculation may take account of any low emission zones and a permission of the vehicle to enter such low emission zones depending on its emission characteristic.