A powerline communications apparatus includes a transceiver communicating over an electrical power distribution wiring of a vehicle and a communications interface carrying a first and second PLC message in a first communication protocol having a PLC automotive network delimiter type, a PLCAN variant field comprising a number of users, user identifications, payload length, payload data, and a repetition number corresponding to a number of times the first PLC message is transmitted over the electrical power distribution wiring, and a first payload for a first user. The PLC apparatus also includes a processor and a non-transitory computer-readable medium storing programming for execution by the processor. The programming includes instructions for transmitting the first PLC message using the transceiver, determining if the vehicle is in motion, and switching between the first and the second communication protocol based on whether the vehicle is determined to be in motion.