1. A navigation system for selecting a route from a starting location to a destination, the system comprising: a user-operable input device configured to receive the destination; a storage medium having a map database describing a road network comprising route segments; each of said route segments having a respective attribute value and a respective energy cost; a processor operatively connected to the input device to receive the destination, and operatively connected to the storage medium and configured to selectively access the map database; said processor being 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 to select a combination of route segments from the database that interconnects the starting location and the destination.