What behavior do you mean by "he has a problem traveling"?
Thor is a very happy-anxious passenger. He gets so wound up and excited about whatever is going to happen or wherever we are going he whines and cries and pants and paces. You would think he was under distress except for the fact that he can't WAIT to get in the car. We've tried desensitizing him by just putting him in the car and driving around with no destination in mind but that is enough to be a reward. One thing that has really helped calm him down is a car safety harness. I think it's a combination of the restraint plus the vest might do something similar to a thundershirt. My car combo is the Ruffwear Load Up Harness combined with their Dirt bag seat cover. Works well in the back seat of my Subaru Outback. The seat cover creates his own space and keeps him from wanting to crawl in the front seat with me.