When the teen drivers listened to their preferred music, virtually all (98 percent) demonstrated an average of three deficient driving behaviors in at least one of the trips. Nearly a third of those (32 percent) required a a sudden verbal warning or command for action, and 20 percent needed an assisted steering or braking maneuver to prevent an imminent accident. These errors included speeding, tailgating, careless lane switching, passing vehicles and one-handed driving.