The current SAE classification system for serial data communication protocols encompasses Class A, Class B, and Class C categories. Because of the proliferation of applications and new protocols these three groups are not enough. This paper will introduce and discuss several new categories which are Diagnostics, SafetyBus, Mobile Media, and X-by-Wire. The serial data protocols that fall under these categories are for the most part brand new and will serve distinct and unique tasks. All existing common vehicular multiplex protocols (approximately 40) will be categorized using the SAE convention plus the new groupings. Top contenders will be pointed out along with a discussion of the protocol in the best position to become the industry standard in each category. Future vehicle applications having up to seven different data networks will be presented.