A very promising method for coping with the increasing demands on position accuracy for vehicular networks is cooperative positioning. Instead of adding more and more sensors in a self-contained system this technique aims exploiting information which already exists. This paper addresses a new cooperative GNSS positioning approach which is referred to as Advanced Shared Pseudorange (ASP) method. It customizes broadcasted GNSS pseudorange measurements of collaborating vehicles in a way that they can be applied in standard positioning algorithms. Specifically, in urban environments the increased number of usable satellites improves position accuracy or even makes GNSS position estimation possible in the first place. Moreover, the adjustment of pseudoranges from collaborating vehicles only requires inter-vehicle distance measurements as provided by radio ranging techniques. Thereby hardware costs are kept to a minimum. The capability of the new approach is emphasized by a comparison with other cooperative algorithms and test results of a loosely coupled GNSS/INS position estimation for a simulated urban road-segment scenario.