The GPS technology costs about 0, plus a monthly fee.
The Coker sisters of Marietta, Ga., say they don't mind if their parents electronically monitor their driving, as long as it's done for the right reasons and it's not done secretly.
Ashley, 17, knows her father is tracking her, so she says it's OK.
Well, this type of device will give you that type of data," said Stuart Lamm, president of GPS Mobile Solutions.
Another device would let parents block their teens from texting or making a cellphone call while driving, Lamm said.
Rob Coker says safety is why he keeps electronic tabs on his daughters, which he does now through the "Find My i Phone" app.