It's good to hear you weren't more seriously injured and that your camera survived as well.
On the other hand, perhaps you should consider a smaller camera for the car. I've a Minolta 16 to swap for and I think I can safely promise no worse misadventure than a black eye and two asprin headache if you keep it under 55.😉
Seriously, when I was freelancing, only one photographer I would work with would completely secure his gear... tripods, studio lighting cameras and other kit. He went to great lengths to tie-down EVERYTHING and I really appreciated that.
A couple of years previous to that, I worked for a studio that sent myself and another photographer from Charlotte to Knotsville, in an open paneled van, like a bread truck without racks or dividers, with studio equipment for three-four sets, for several weeks shooting, and only the drivers seat. We took turns driving and the other sat in a plastic cafeteria chair that slid everywhere. Needless to say, the Smokies were lots of fun...not!:bang:
The amazing thing was, three weeks latter, we climbed back into that van and made the return trip. Even today I have a hard time remembering if it was the stupidly of youth or simply being 'job scared' that got us through.
Nowadays I try to tie my bag down every time I get into a car.
Cheers