LoJack used to be the go-to company for this. No more. Classic LoJack had good privacy. It's a box hidden somewhere in the car, with a connection to vehicle power. It has a transmitter, but normally doesn't transmit. If your car is stolen, you report this to the police, which report it to LoJack. That broadcasts an ID over a subcarrier of some local FM broadcast station. The receiver in the Lojack unit listens for th…
Outstanding name! Their marketing team has a wicked sense of humor.