1300 hp mercury comet brake failure crash
Remember an object in motion, will stay in motion until something stops it.
By positioning yourself against the object that you will collide into, you are minimizing the momentum ahead of the sudden stop.
Of course if the occupants had shoulder belts, those belts would have limited the forward motion and the sudden stop would occur between them and the shoulder belt, with the shoulder belt being much softer than a dashboard.
