Yes. Always. I worked as a paramedic for too many years not to know what not wearing a seat belt can do. It's not pretty. Even when the accidents aren't fatal, the facial injuries are appalling.

Buckle up. Please. If you don't do it for you, do it so some tender-hearted medic doesn't have to come scrape you up out of your car or off the pavement and live with that memory for the rest of his/her life.