Try ginger tea or ginger lozenges. Safe when pregnant, and for some people it eases motion sickness. Also, bring along a cold damp washcloth in a sack of ice, and put it on the back of your neck if you feel queasy.
I get car sick ever since my first pregnancy, but never when I'm the one driving. I take Dramamine when I'm going on a trip and someone else is driving. But I wouldn't take it if you are driving (makes me very drowsy) and I don't think it's safe during pregnancy. Sorry!