On average, NHTSA estimates that 9,500 lives are saved every year by wearing seatbelts. Unfortunately not everyone takes the time to buckle up or they may do so incorrectly. The lap belt needs to fit over your hips, not your abdomen, and the shoulder belt should lie on your chest and over your shoulder. Remove any slack from the belt.
Seatbelts have several functions in the event of an accident. They prevent passengers from being thrown from the vehicle, reduce the risk of collision with the steering wheel, windshield and dashboard thereby minimizing injuries. Seatbelts also distribute the shock of the crash over a larger part of the body, which disperses the shock causing less chance of acute injury. Another function is keeping you in a position that allows airbags to be the most beneficial to you.
A new innovation by auto manufacturers is the pretensioner seatbelt. This is similar to the air bag in that it can only be used one time and will need to be replaced after a crash. In an accident, pretensioners retract the seatbelt to remove excess slack. The seatbelt still needs to be adjusted as snugly as possible, as pretensioners are not powerful enough to pull you back into your seat.
Another new innovation in seatbelts is the energy management feature. This feature allows seatbelts to release enough slack to prevent the shoulder belt from allowing too much force from being exerted across your chest. This feature includes load limiters built into the shoulder belt retractor and/or tear stitching in the webbing that causes the seatbelt to extend gradually.
More auto manufactures are providing adjustable upper belts for a more comfortable fit. This feature is available with the three-point seatbelts and allows the height of the shoulder strap to accommodate a person's size. The adjustable seatbelt is usually equipped in the front seat but some manufacturers now provide the option for the back seat as well.