car
Well there is your problem. Buy a ute and put them in a proper made dog box.
Obedience training.
x a ga-zillion-million-ty. Well trained dogs are very happy dogs with very happy owners.

Crate training is supposed to be a good thing (I hear) but a well trained dog doesn't need confinement in my humble opinion.
When training all emphasis should be on the good behaviour only. Reward the dog when it's "quiet" and it will soon learn that "quiet" is good because it gets reward - use a word eg: ssshhh / quiet / Oy / and then reward - draw out the length between the word and the reward ... soon enough they associate the word with the peace and harmony and eventually you'll get it in the car.
Lots of stuff on Utube in this regard ... but I'll find the link of the bloke that
I think makes it easier ... and he's got a video for everything concerning training.
Practise - Practise - Practise. Consistency - Consistency - Consistency. Patience - Patience - Patience. Love - Love - Love.
Good Dog.
Kit_e