A system and method for determining the position and velocity of a plurality of vehicles relative to a host vehicle using GPS data. The method includes building a graph of the vehicles that define weighted baselines between each of the vehicles and the host vehicle and each of the vehicles where the weighted baselines define a geometric dilution of precision between the vehicles. The method then determines the optimal baseline between the host vehicle and each of the other vehicles using the weighted baselines based on the lowest geometric dilution of precision. The method then computes the relative position and velocity between all of the vehicles and the host vehicle using the optimal baselines.