This document provides a summary of the suggested OBDII protocols by manufacturer and model year. It shows that the most common protocols included ISO 9141, KWP2000, J1850, and CAN. Over time, there was a transition from older protocols like ISO 9141 and J1850 to newer protocols like KWP2000 and CAN. By the late 2000s, CAN had become the dominant protocol for most manufacturers.