My husbands dog would get car sick till we started taking her on short trips to the ice cream store.
We would buy her just a small cone, a baby one.
After about one week of doing this every other evening she stopped getting car sick and looked forward to car rides.
We stopped the ice cream and gave her dog cookies sometimes.
She was able to travel over 500 miles one way with no problems.
So make it a happy car ride and I bet Doppler will soon love car rides as much as our girls do.