1. As soon as you hit the water, open your window. This is your best chance of escape, because opening the door will be very difficult given the outside water pressure. (To be safe, you should drive with the windows and doors slightly open whenever you are near water or driving on ice.) Opening the window allows water to come in and equalize the pressure. Once the water pressure inside and outside the car is equal, you’ll be able to open the door.
2. If your power windows won’t work or you cannot roll your windows down all the way, attempt to break the glass with your foot, shoulder, or a heavy object such as an antitheft steering wheel lock.
3. Get out. Do not worry about leaving anything behind unless it is another person. Vehicles with engines in front will sink at a steep angle. If the water is fifteen feet or deeper, the vehicle may end up on its roof, upside down. For this reason, you must get out as soon as possible, while the car is still afloat. Depending on the vehicle, floating time will range from a few seconds to a few minutes. The more airtight the car, the longer it floats. Air in the car will be quickly forced out through the trunk and cab. An air bubble is unlikely to remain once the car hits bottom. Get out as early as possible.
4. If you are unable to open the window or break it, you have one final option. Remain calm and do not panic. Wait until the car begins filling with water. When the water reaches your head, take a deep breath and hold it. Now the pressure should be equalized inside and outside, and you should be able to open the door and swim to the surface.
And some youtubey goodness.
What an awesome doggy!!!!!! I wanna hug her!