Distracted driving is a major risk factor of car crashes, and the National Highway Traffic Safety Administration reports that about 20 percent of accidents involve some form of

distraction. Since teens are about four times more likely to get into accidents, the Children's Hospital of Philadelphia and State Farm each conducted studies to determine how multiple passengers can distract teen drivers.

"These studies help us understand the factors that may predispose teens to drive with multiple friends and how these passengers may contribute to crashes by distracting the driver and promoting risky driving behaviors, such as speeding, tailgating or weaving," said Allison Curry, the lead author of the study and the director of epidemiology at the Center for Injury Research and Prevention.

The outcome of both studies revealed that teens are more likely to engage in risky behavior behind the wheel, drive aggressively and get distracted by something going on inside the vehicle.

Parents may not be able to control what goes on in the car when their teens take to the roads alone, but they can ensure the vehicle is in top shape. A car that runs well is less likelty to have something go wrong that could cause an accident, but repairs can be expensive. An extended auto warranty can cover the cost for certain parts so parents don't have to break the bank to keep their kids safe.