[alaskayorkie]

I think a Thundershirt is worth a try. I have one who shakes during thunderstorms and fireworks, and the shirt definitely takes the edge off. It's not exactly a miracle cure for us, but it's a noticeable improvement. We put it on him any time he seems anxious.

I wouldn't give up on the treat idea. Maybe do some training sessions where you do something fun in the car when it's not moving. Toss a favorite toy. Give him a favorite chew toy, like a stuffed Kong or a bully stick. Start slow, just a few minutes a day until he gets over the fear of the unmoving car. After a week or two, start the car and keep playing. Later on, you can try driving a block or two, stop, play, etc.

There's an over the counter product called Rescue Remedy that can calm them down too, but for me that's a last resort.

Good luck! I feel for anyone with an anxious Yorkie.