CAN Bus
Vehicles use the CAN Bus or variations of. Its behaviour is that a client on the bus broadcasts to all other clients on the bus, providing the bus is currently free or only a lower priority broadcast is underway. Its up to other clients to look at the message and decide if they want to do anything with it.
To be honest it's a great design for the scenarios it was intended for. However, integrating it with the public internet provides some very specific design challenges that perhaps it isn't best suited for. All devices on the bus are trusted by default. Anything on a public network should be untrusted by default.
Biting the hand that feeds IT
