I don't think David made it through the car accident...
I saw this movie in 2002 and I originally bought the frozen-to-the-future ending but watching it again all these years later I'm not convinced.
I believe the day of the accident was the day David died and the rest of the movie is either a vivid death dream or some type of transitional purgatory. I notice the particular shot of the car going off the bridge smashing into the wall so graphically was meant to give us a clue that this was nothing anyone could survive.