>>1
The best way to get out of a car which is underwater or sinking is to:
First, open all the windows. The water pressure outside doesn't allow you to open the doors, and the faster you can get out, the closer you'll be to the surface assuming a fairly deep lake.
Second, unbuckle your seat belt. It disallows most movement, and, as such, is a major hindrance.
Third, once the water has equalized enough to allow you to open the door, do so. Doors are an even larger deterrent in your attempts at escape due to their solidity.
Four, swim to the surface. Human lungs aren't able to absorb oxygen from the water, which you are now submerged in. Also, ignore the baby in the back. Babies are excellent swimmers.