Notice in this test crash of an older car, the car has a very rigid frame, so it comes to rest almost immediately while the body of the car keeps going at its current velocity. The body has no crumple zone so it comes to rest as it hits the wall and the people are then brought to rest immediately as they strike very solid items within the car. Remember, it takes the same impulse (J=Ft) to stop the people in the car. This car uses a small time, so the force must be huge...and quite deadly.