Lindsay, My puppy girl before Star, Tippy, got car sick the first time we went on a long trip together. She was about 4 months old at the time also. It only happened once. I think she just needed to "get" her car legs... After that time she loved the car and was always willing to go any place just because she liked watching the view from the car.
I hope you find it to be the same with Cooper :-) Marilynn and Star.
