Our carsickness days are over since my girls started sitting in a secured pet booster car seat. Since they are raised up...and can see out of the window...no more barfin'!
Here's a link to what kind we have...(they each have their own seat):
http://www.snoozer-dog-beds.com/dogcarseats.htm
The covers are beautifully made and they wash & dry like brand new, too!
Best purchase I ever made for my girls!