Just unplug the cellular modem.
I have three "dumb" cars and I'm going to continue to baby the crap out of them. I have zero interest in anything new. Maybe a Mazda if push came to shove.
There's a good chance the modem is on its own fuse. There's also a good chance the modem is 4g only, so whenever that gets shutdown, the car will be trackerless, as happened to cars with 2g or 3g modems. :D
