I hitchhike very often. What should I do when the driver drives too fast, should I say something to him? Can I talk to my friend while we’re in the car?
You must behave like a guest - do not disturb, do not comment, do not litter, do not eat, do not make noise, do not talk on the phone (unless it's urgent and you've asked the driver for permission), do not smoke. In short, be polite. This question was answered by Rabbi Yaakov Ariel