Jeanniewes,
We had a dog that hated to travel so we generally let him stay with friends. However, a few times we did travel with him, we gave him about 1/3 tablet of Benadryl and that did help him quite a bit. He was about 18 pounds. We have read various articles that say you shouldn't give dogs benadryl but our little mutt was close to 18 when he finally died so I guess the benadryl didn't hurt him any.
Our present dog, a rescue Shih Tzu, starts off trembling but once we are headed down the road and she knows she's not going to the vet or the groomer she does fine. I will say that she does much better in the GMC Envoy where she can lay on top of luggage and see out than she does in the RV where she can't look out the windows. Also the RV is noisier than the Envoy. I've been trying to figure out how we are going to take care of that. Maybe if we strap a big pillow on the sofa so she has a cushy place to lay and she can see out, she will be happy.. Lol, what we humans do to take care of our fur babies...