The only suggestion I have is to put her in a kennel when you take her in the car.
Couple of questions. Does she get crazy when you are getting ready to leave your house? You may have to spend some time with her and train her to stay calm. Kind of like Pavlov's dog. Practice in the car in your own driveway. Bring her in and out of the car and when she behaves, reward her. Of course you don't want to feed her too many treats at a time. But, maybe a few times a week, do these exercises. Hopefully that will help. As I understand, yorkie-poos are very receptive to possitive reinforcement. Hope all goes well.