1. A hybrid vehicle navigation system comprising: means for determining a sensed position of said vehicle from a Global Positioning System; means for determining a calculated position of said vehicle from at least one dead reckoning sensor; means for comparing said sensed vehicle position and said calculated vehicle position with a location selected from a plurality of candidate vehicle positions in a map database containing pre-stored locations obtained from an external system; means for computing a plurality of correction factors, one for each sensed position and one for each calculated position; said means for computing being effective for choosing one of said plurality of correction factors that, when used to correct said vehicle position, makes said vehicle position correspond to said location; and means, based on said selected correction factor and an associated one of said sensed position and said calculated position, for correcting said vehicle position.