Our Sam was a 2 year old Shi-poo when we got him a year ago in January. He got sick in the truck on the way home from his hell hole!, We tried to get him accustomed to the riding.
We tried the Travel capsules but they did make him more relaxed but did not stop the motion sickness! I asked the vet and he gave me 2 Dramamine pills and told us to give him half and see how he handles it and if he gets sick, give him the other half.
Well we gave him the half and took him about 35 miles to the dog groomer. Made it all the way to the groomer, until we pulled into the parking lot and he lost it!
We gave him the other half for the trip home, he got sick again.
We were patient, I read about just taking short rides, like around the block. We did this and before we started out,we just put him in the vehicle and sat with him and talked calmly with him. We would stretch those rides out and within 2 weeks he was riding, no pills and kept the rides as short as possible and in fact he rides on the console next to me in the truck see he can see where he is going. He still had an occasion or two that he got sick but we were making headway! He wont sit in the back seat unless we have a grandkid or 2 with us. Now he enjoys the rides and when we are going through towns at lower speeds, he will get in the passenger seat and want to stick his head out the window!
One thing I read that I think really got the job done for him was keep your dog facing the front!
One of his last events was when I took him on a random 5 mile trial and we did good until I did the big U-turn to return home and he got sick just as I turned. There is too much motion all at once when he would sit on my wife's lap facing the side window.
All total, about 5 weeks or less and he rides 2 and 300 mile trips and never gets sick and like I said, he enjoys the view from the console!
I would advise to be patient and don't scold him! I bet he wants to ride. As we drove while working with Sam, we made sure he did not turn to look out the side windows. I think that confidence builder for him! Good luck! Just an aside, the vet didn't want me car train him on Dramamine and suggested using it only 50% of the time if he was to get to a point where he could go a little!
The grand kids get a kick out of seeing him on that console, when I turn a corner or go around a sharp curve I say "lean into it Sammy", and darned if he doesn't lean the way he is supposed to so he doesn't slide off his perch!