Auto accidents are the number one killer of teens. Almost 6,000 teens die every year in auto accidents. Teens account for 14% of all motor vehicle accident deaths. 5,288 teens died in motor vehicle accidents in 2005 in the U.S. Crashes are the leading cause of death among teens, accounting for more than one-third of all deaths of 16 to 18 year-olds.. Parents are often relieved when their teen starts driving because they don't have to chauffeur them around anymore. The two primary factors that cause teen auto accidents are immaturity and inexperience. Teens are likely to engage in risky behavior, such as: speeding, not wearing a seat belt, passengers in the vehicle, night driving (9pm - 6am), alcohol, following other vehicles too close, passing inappropriately, & driver error. Young drivers tend to overestimate their own physical and driving abilities and underestimate the dangers on the road..