In Florida, the DNR papers are required to be on yellow paper, and suggested to attach to your refrigerator door. I carried the DNR in my pocket wherever we went, as we went to the emergency room several times for breathing issues.
One time, we were at the movies when Krissy said she had a hard time breathing. I wheeled her into the parking lot, and judged that we could get her to the hospital faster than an ambulance could arrive so we drove. On entering the ER, I went straight to the triage nurse, interrupted her work with another patient, and said firmly, "We have a terminally-ill, paralyzed patient with extreme difficulty breathing. We need to go ahead of the line." We were seen immediately.
The problem with driving yourself to the ER is that you're low priority. Arrivals by ambulances always get in first.
But one time, I was in the ambulance with my PALS (we were inseparable) and the ambulance got lost. I had to navigate his way out of my neighborhood to the hospital!