I really shouldn't post before I've had my first morning cup o' coffee.
McQueen is right. I was thinking of the voice-activated recorder, whose alkaline triple-A batteries I had to replace every day. The phone charge will last nearly a week.
I bought a cheap $40 BoostMobile GPS-capable phone, and disabled all of its sounds. Put a little piece of black electrical tape over the speaker, just in case. Bought $20 worth of minutes, and an app called MapQuest Find Me -- $3.99/mo. Hid it in my son's baseball equipment back in the trunk of her car. You then log on to a secure website, and you can view where the car (phone) is at all times. (It needs to have a clear "view" of the sky, but even jammed in the baseball bag, it worked fine about 90% of the time). You can even set alerts, where it will shoot you an e-mail when the phone gets within a predetermined distance of a selected location (ex.: 100 yards of OM's house, or 200 yards of my wife's place of employment, etc.). I was able to capture screenshots of her car parked at OM's house, contemporaneous with my journal noting that she told me she was at work, etc.
It also aided me with my amateur sleuth, as I was able to give her my wife's driving patterns, and locate her when she'd lose her.
If the car is partially titled to you, I believe this is legal, but check your state laws. It was perfectly legal here, in Florida, as the law deems the car to be your personal property and you are allowed to keep track of the whereabouts of your property.
