Try opening a car door on the high side of a car parked on a side hill. You will be lifting much weight. All for 'side impact' mostly from SUV's and large pickups most of which should not be on the road in the first place. Very few cars weigh less 3000lb now. This is environmental insanity. So called air bags should not be mandatory. I have a friend who lost the sight of one eye when he scraped a center divider and the 'air bag' inflated. the products of the explosion is not air but nitrogen laced with lead. Just fasten your seat belt.