Route planning system for vehicles

A navigation system includes a user-operable input device configured to receive a desired destination. A storage medium stores a map database that describes a road network comprising route segments. The map database includes, for each of the route segments, a respective attribute value and a respective energy cost. A processor is configured to analyze the route segments in the database in accordance with a predetermined optimization algorithm that considers both the attribute values and the energy costs of the route segments in order to select a combination of route segments from the database that interconnects a starting location and the destination.