This was on my Obedience forum - The video takes a little while to load, and it is in German - but watch the whole thing - it is amazing and disturbing. I'm getting crates for the back of the car (not on the seat!)
Yeah, I worry about that all the time. Rocket is loose in the back of my SUV. He should be in a crate, as a best solution. While there is really no way of preventing injury to him, I need to minimize it and keep the people in the seats ahead of him safe.