What you want is T-mobile Sync Up. Its T-mobiles equivalent to what your referring to and basically makes the vehicle a hot spot. Of course it can also be used to monitor the location of the vehicle and such. You just plug under the dash in the OBD port that mechanics use when running diagnostics on your vehicle.
You can check if your vehicle is compatible by going to this link:
On a side note I believe it will count as its own line so that is a thing and there is actually easier ways to keep track of your teen if you really feel a absolute need. For example you can track of his/her phone.
Manage your T-Mobile account