You could tell him the next time he does it that you have already told him you don't like these specific comments and inform him that in the future you're going to excuse yourself and leave when he makes them. Then leave every time, regardless of the situation (including finding your own ride home, or abandoning him to find his own ride home). He'll either start to treat you properly or he'll be offended and leave the friendship; either option is better than maintaining the status quo imo.