Ping to #41 for your thoughts.
The weight of the front right corner of the car, was the first to be un-supported.
The front right of the car began to drop, imparting a bank to the right, a spin around the longitudinal axis of the car (front to rear centerline axis).
As the rest of the car left the bridge, it kept banking hard to the right and landed roughly inverted.
Because the front end of the car also landed first in the water first, that acted as a drag.
Yet, the momentum of the car, continued to bring the rear end of the car around to a point where finally, the car was both, still inverted, and its fore-aft situation (the front of the car) aimed back in the direction in which the car had approached the bridge.
During that action of the car, Ted Kennedy was probably thrown out of the car, in a direction away from the bridge.
To give you an idea of the forces acting upon him, take a thin book, maybe 8 x 6 inches and hold it horizontally in front of you, and imagine it to be roughly the plane of the car, just prior to the car's leaving the bridge.
Imagine a driver's seat. Put a round-like object, where you would imagine Kennedy to have been, immediately prior to the car's leaving the bridge.
Now, in one motion, rapidly drop the front right corner of the car and bank the car to the right. Play with that a few times, and you will see that the forces on Kennedy, were effectively ejecting him from the car.
Then, repeat the exercise, but this time, put your object on the book where you imagine Mary Jo to have been, in the front right passenger's seat, immediately prior to the car's leaving the bridge.
The forces of the car, its action, the water upon impact, were all trapping her in the car.
While the forces of the car, its action, were catapulting Kennedy from the vehicle.
Mary Jo was probably stunned, and when she recovered, she found herself at the top of the water in the air reservoir.
If she had not been partying, had not been ill, she might have found her way out of the car; but it was late, she was tired from a long day and the party, and she was not feeling well, so she clung to life as it still presented to her.