For anyone who needs to look into it in the future: ambulances have oxygen, defibrillators, and trained EMTs, so they will cost more. Patients with COPD, on oxygen for other reasons, or with a history of multiple or recent cardiac issues or strokes should probably go by ambulance. Often patients who are stable but have mobility issues can be transported by ambulette, which is basically just a wheelchair-accessible van, and I believe the drivers receive CPR training. Obviously the ambulette is cheaper. Patients who can stand on their own may not even need an ambulette.
Longer distance trips will obviously cost more, IIRC but it's a bit like a plumber, a lot of the cost may be just calling them out and having their expertise there for any length of time. (I was an EMT, but I really was not involved in billing.)
-Looking to FIRE in the mid-2020s, which would be our mid-50s.