First, if the car fell into the pond (God forbid, of course) from the embankment or bridge, do not leave the vehicle until it is full immersion in water or, if small, until the wheels will fall to the bottom. Otherwise, the burst stream of water can be your gravedigger.
When it became clear that the car is sinking, the first thing you need to do is to close the Windows to slow down the process of immersion. After that, it would be good to turn on the headlights, which may serve as a signal for potential rescuers and to help subsequently to find and raise the car (the electrical system usually continues to run for some time).
If we were just driving along, trying to lower the back seats to have more space for movement. Further, using the time until the machine is sinking, you need to look for pillows, convolution, or some clothes put everything that you can find for yourself, in order to climb the ceiling.
Along with this, it is necessary to try to manage to remove everything that can hinder movement: coats, heavy clothes, shoes, laces and belts, — all this, in the current situation, we do not need.
And when the water filled the cabin and exceeded the level of the door, that is the principle of pressure equalization is made, it should be safe to open the door. This way is preferred if the machine is left intact. Otherwise, a window POPs hand rests on the roof, the person is turned inward, and then head forward we get out of the car.
In case, if the Windows don't open, have to break the glass. They usually prefer the front or back, which more than any other. This, however, depends on the position where the car is after immersion and which is almost never horizontal.
In order to break the glass, you will need to wait until the last, then beat with a blunt object, and not in the center and in the corner of the glass, where the resistance is less. For this purpose, may serve, for example, a fire extinguisher, which should always be in the cabin, and sometimes it is enough to press your feet and squeeze the glass from the rubber gasket, not even breaking it.
And most importantly — as in any crisis situation, the most important thing here — self-control, because panicky by, we do for ourselves we begin to be dangerous.