CAN Bus
https://makezine.com/2016/04/08/car-hacking-tools-trade/
Types:
- High Speed (Differential); usually ~500 kbps, rarely up to 1mbps 
- Low Speed (Single Ended); non-critical such as light, door etc. control 
- Fault Tolerant (cut wire defaults to low speed; air bag) 
- CAN FD (newest)