IIRC , Mary joe suffocated in an air pocket in the back seat . That leads me to believe teddy didn’t even try to save her .
I’m sure. Otherwise how could he have enough time to hightail it back to the hotel sneak in and change his clothes and look as if he wasn’t a part of it all.
You are correct. Drowning would have been quick. Suffocation must have been agonizing as she waited, hoped and prayed for help to arrive.