Final answer:
If your vehicle becomes submerged and you are unable to roll down the window, you should wait for the vehicle to fill with water and then break the window to escape.
Step-by-step explanation:
If your vehicle becomes submerged and you are not able to roll down the window to escape, you should wait for the vehicle to fill with water and then hit the bottom of the window with a hammer or sharp, hard object to shatter the glass. Once the glass is shattered, carefully push it out with the hammer and swim to safety.