"...at least 30 minutes..."

I used to work I-5 in central CA, and a 30 min eta for an ambulance was FAST. I have had to wait, in fog season, for over two HOURS for an ambulance to arrive. But still, in almost 100% of those cases, leaving the victim in the vehicle is the way to go. It is possible to do CPR on a person still upright in a car seat. Not easy, but doable. If you do have to remove a person from a vehicle, you need to know the proper procedure to do so which will cause the least amount of additional damage. And I know of more than one case where a victim, thinking that he/she was OK, hopped out of the vehicle with a cracked vertebrae, then suddenly collapsed, never to walk again. In any collision, maybe excepting a real minor fender bender, you have to assume a possible c-spine injury...