Once a dog is use to the car, out and about works. My guys have netting made for the interior of my van to make seperate areas, but they can easily stand up and turn around- but if I had to stop fast or someone hit me from behind- they could not go flying . ( will get a picture tomorrow- looks like cargo netting on a pick up truck but it runs up and down inside a van verses the cargo area of a truck.
I think for now, just let the dog feel secure. Nerves have a way of making dogs sicker faster.