I think that I would try a funny approach. You could point out that bikes don't have exhaust pipes, radio antennas, seat belts, or windshield wipers. You sould pint out that cars don't have kickstands, handlebars, or reflectors. You could also say that bikes don't use gas, parking spaces, clog up the roads in traffic jams, and are an excellent form of exercise.
As for the rules of the road, agree that all vehicles should follow the rules of the road, and it would be helpful if the drivers of cars could set a good example for the rest of us. Maybe they could start a) obeying speed limits, b) stopping completely at stop signs, c) signalling when turning, and c) refraining from driving while intoxicated.
If you strike the right humourous tone maybe you could accomplish your mission of countering his drivel while being upbeat. Good luck and I hope this helps.