I had a dog many moons ago that would get carsick and I noticed that if I left the window at least 1/2 way down so the air could blow on her that it helped immensely. I also bought a little fan that I mounted on the console between the front seats for when it was too cold to open the windows and just that little bit of air blowing worked. She would actually sit in her carseat and put her face as close to the fan as she could. Might be worth a try
