If your dog gets car sickness start be getting him okay with the cat. Just sit in the car together with the engine running and don’t go anywhere. Let him relax and enjoy the company and time with you. Increase the time you spend in the car until you can turn on the car and go for a very short drive without the dog getting sick. Drive for a couple of minutes, then get out and walk around. It will be good socialization and the pup will realize that car means new places and people. Increase the time and distance. It takes patience but take the dog every chance you get. We once decided to get some meds from the vet, but we had very bad results. He was sedated but no less anxious and still his stomach was very upset. And in addition to all of this he didn’t trust us to hand feed him for 3 days. Eventually we got him used to the car and he now goes everywhere with us and “going for a ride” iss the highlight of his day. So sorry for the long response but please don’t drug your dog, give him something more herbal or natural (one brand has already been suggested) and work on him slowly. Good luck and I hope you see good results! :-h