How to avoid getting car sick?

I always get car sick for long car rides that are about more than an hour. I'm going to San Francisco with my good friends next week and I don't want to barf in front of them..again. You know what I mean? Also my friend's parents are taking us so it's an even more complicated situation and more embarrassing. I threw up last time when I was coming BACK from Santa Cruz because my friend was being stubborn and told me to go on a lot of crazy rides like less than 5 minutes after I ate a lot of food. Then I went directly into a car and rode home. -__- I've always gotten car sick since I was young. But I usually sleep during the car ride but I don't want to miss out on everything by sleeping in the car while with my friends! I hate feeling left out.. I was fine on the ride TO Santa Cruz but I did feel a bit dizzy. How can I avoid getting car sick and embarrassing myself? Also is it true that if you feel sick and you drink water you feel even more sick? I tried eating minty things while in the car.. but it made me feel worse.. It's an hour ride there by the way..