Yes. Correct usage of a seat belt (Making sure that it is placed correctly over your hips and shoulder) can save your life in the event of a crash, also airbags are designed to work alongside seat belts and so will not save your life on their own. Apart from saving your own life, if you have other passengers in your car wearing a seat belt can also preserve their lives, as if you are NOT wearing a seat belt you become a human missile, putting those who are wearing seat belts at risk of injury or even death, this is particularly the case with those in the back seat.