Fiona does the same thing, only she loves to go for car rides! Our vet said to give them about half a(I give a little less than half, and I have a big yorkie) tablet of Dramamine about 20 mins before you leave.
Worked like a charm, and you can get the less drowsy kind. We had a 2 day trip (14 hrs) she did great. I have asked two separate vets to make sure this was ok, and they both suggested it, as well as her obedience school "teachers".
Hope this helps!
