See how much space is between Tech Editor Fred Williams' butt and the seat (arrow)? He had the seatbelts cranked down as tight as he could get them but they still stretched. Almost 2 inches. To be really safe, you often need the belts tighter than you can stand them to be, but even more importantly you need to buckle them up. It's dumb to not have them tight; its even dumber to not use them when you have them.