If your child drives a car, for example, from Audi A5, of course, is the ability to use CarTrack to determine where it is located. Of course, you can not assume the worst and not too interfere in his life too much, but this page is not of parenting advice. Well, you can be sure that in this way you check exactly where your child is.
If you fail the installation of the smartphone in your car, you can simply install the app on your smartphone to your child. It will be actually a better solution, because you'll know where the child is, not only will lead the car. However, the risk that the child will not take your phone or discover that you have installed in it such an application. You must use the appropriate method corresponding to the habits of your son.