Hello wiggal, lankeela, naflharrison.
I have just started driving, and invested in a doggy car harness, as suggested. It fits round your dog (or pup, wiggal!) and then the back seatbelt is fed through the loop behind the harness, so your dog is attached to the seatbelt and held in place, but can still sit or lie down comfortably.
As I am a new driver, I didn't want the distractions of a wandering dog in the back of the car (also, isn't it illegal now?), and so I put a fleecy blanket down across the seat, strapped Jack in....and he loves it! He fell asleep the first time I took him out for a little drive!
I would really recommend them, wiggal. Cleo will probably only need a small size for now, and you may have to reinvest as she grows. Maybe half a herbal tablet before the journey too? Ask your vet first though, just in case.
lankeela is right too, don't feed her. I know what you mean about never tiring, but make sure she has had some action before she gets in the car, and a chance to toilet, because then at least she won't be so restless! FIngers crossed...
Is Ashke going with you too?
Have a great time! Cuddles for the fur-family from me :) x