Most teens are susceptible to peer pressure, which can lead to risk-taking. In a study analyzed by NHTSA, teen drivers were two-and-a-half times more likely to engage in one or more potentially risky behaviors when driving with one teenage peer compared to when driving alone.
The more, the scarier: Research shows that the risk of a fatal crash goes up in direct relation to the number of teenagers in the car.
Again, the law is not enough. As a parent, you need to establish and enforce ground rules: No more than one passenger in the car at all times, and preferably none.