1. A vehicle communication system in which an in-vehicle battery is charged from an external power supply connected thereto via an electric power line and external communication using the electric power line as a communication conduit is enabled, the vehicle communication system characterized in that: through communication performed during charging, information regarding either the geographical area where the charging is being performed or control parameter information set in accordance with the geographical area where the charging is performed is obtained, and a control parameter of the vehicle is set in accordance with the obtained information.