Yes they do - are you looking to just use a magnet to stick it on covertly or actually install it.
The covert technology has two options:
1. Passive technology - it's a data logger, you need to retrieve it before you can get the info.
2. Active Technology - you can actively track it, but you will need to watch for the battery life. Most batteries die after about 72 hours if tracking at about 1 minute intervals.
If you are looking to just install gps technology and can access the vehicles harness or OBD, then there are a bunch of options. Check a free website "vigilancegps" for info on server software, devices and their software and how to install them.