She may be experiencing motion sickness. What worked for me was crating, opening windows getting good air flow, and even covering the crate with a lightweight sheet.
She can be taught to accept the crate. Take your time and have patience. It really is much safer for her to ride in a crate. It would be preferable to sedating her which might mean she is kinda out of it when you get to your destination.
Archie gets excited riding but settles down fairly quickly. However he knows, when we get close to our destination, he is all noise and wiggles in the crate.