This SAE Standard specifies system requirements for an onboard vehicle-to-vehicle (V2V) safety communications system for vehicle classes of 2, 3, 4, and 51, including standards profiles, functional requirements, and performance requirements. The system is capable of transmitting and receiving the SAE J2735-defined basic safety message (BSM) over a PC5 Sidelink V2X (mode 4) communications link as defined in ETSI Release 142,3. The system uses Institute of Electrical and Electronics Engineers (IEEE) 1609 standards for network and transport layer communciations, as well as security.