With the progress of car electronics the saving of the wire number by use of information system such as LAN is said to be inevitable. In case of the introduction of LAN into car where an accident might be vitally related to human life, the system is requested to have higher processing ability against the crowdedness of signals.
In order to consider the conditions of such kind of LAN, we carried out a simulation study to find the dependence of the retardation characteristics on the modes of token control and on the status of informations.