As a car stereo installer, I have personally searched for and removed 14 GPS tracking systems. I have also installed one. In the latter case, the parent had us install the unit so he could monitor his sons driving habits. In the ones I have searched for, they were almost always installed by the husband/boyfriend to monitor the wife/girlfriend. Only in one case have I ever found the roles reversed. The saddest part of all of this is when I confirmed the customers suspicions, they were not as surprised as dissapointed. It is sad that we, as humans, are so untrustworthy that we feel the need to spy on one of the most special (hopefully) relationships in our lives.

By the way, installing one of these units on a car that doesn't belong to you is illegal!