A rear-end crash occurs every 17 seconds in the U.S. But many cars, especially those made before 2009, offer inadequate protection from the whiplash injuries that can result. Whiplash refers to the rapid snapping back of a person’s head during a collision, which hyperextends the neck and damages nerves and ligaments, often resulting in chronic symptoms such as persistent pain and lack of mobility. It can occur at crash speeds as low as 10 mph.