Way to ratchet up the tension! You definitely hit on one of my own fears (drowning) so I was biting my nails. Good job!

Without a baby, she might have survived by unbuckling her seatbelt and being ready to swim of the car.
With the baby there… ugh. Need Asimovian robo-help.

To swim out of the car. Damn uneditable comments.

I love the details and how the pacing keeps the reader on the edge of his/her seat.