Turning kids loose in the car on public roads worries parents more than drug addiction or unwanted pregnancy, according to a study. It's one thing to sit beside them and coach as a second set of eyes and ears, but when you're not there, trouble can multiply. The Centers for Disease Control reports that car crashes are the leading cause of death for teenagers in the United States. Over 2,000 teens were killed in car crashes in 2016, and despite being just 7 percent of the population, they accounted for 11 percent of the total cost of motor vehicle injuries in 2017.

With new wireless communications technology more affordable than ever, everyone from automakers to cellphone carriers and electronics stores is now jumping into the passenger's seat, rushing to become the parents'eyes and ears as teens journey out on their own.

Most of the systems have similar features. Parents can set alerts when their teen driver exceeds a pre-set speed limit or goes outside designated geographic boundaries. Some systems can locate the car on an online map in real time and let parents check a summary of their teen's driving behavior. Most devices also track the car's service needs, such as oil changes, tire rotations, and diagnostic reports of any check-engine readings.

The most aggressive teen watchdogs offer geomapping and remote alert functions and require internet connectivity with a monthly fee for service. If your kids object that you're "spying" on them, just remind them that if you really didn't trust them, you wouldn't let them drive your car at all.