The self-supplied navigation concept is based on the combination of the floating car data technique and the dynamic route guidance service in the same vehicles. The gains obtained by the users of such system are, obviously, closely related to the percentage of equipped vehicles. This study shows concretely this relation relying on the use of a large scale microsimulator urban model, the Lausanne city case. Finally, limitations due to the fact that the same vehicles are providing and exploiting the traffic information are clearly emphasized.