If a car falls into the water and becomes submerged, you cannot open the door until the interior is flooded.
CONFIRMED
The pressure differential between outside and inside when the car is submerged is too great for a man to force the door, and the pressure must first be equalized, which means the interior must be flooded first. But it should be noted that Adam was forced to resort to emergency air in his first test. A second test later showed it to be possible to escape the car simply by opening the door, but only by remaining calm and not attempting to open the door until the interior is well and truly flooded, so as to conserve oxygen while holding your breath.
You can open a window in a submerged car by attempting to break the window using a window-breaking hammer.
CONFIRMED
The device is designed with a pointed tip designed to shatter tempered glass. The hammer breaks the window on the first try.
You can open a window in a submerged car by attempting to break the window using a spring-loaded center punch.
CONFIRMED
The point of the punch can work like the tip of the hammer, and punches are sold for the purpose of breaking window glass. The punch breaks the window on the first try.