Not much of a driver myself (a New Yorker through and through), I frequently do grip the dashboard. I stomp an invisible, non-existent passenger-side break. I grab at straps. It drives my drivers crazy. Which makes me crazy. It's simply not a fun way to travel.
But, since one particularly trying seven-hour trip with a friend about seven years ago, I have worked very hard on modifying my behavior. Realizing this is purely about trust and control and fear (I was in a scary accident with my mom at age 14), I do my best to actively let go and relax as soon as I get in a car. Here are some things I do. They may help you in similar situations, i.e., when you are feeling out of control yet are not in any actual danger--in planes, cars, in-laws living rooms, etc: (More)