Just when I was starting to think I am a lunatic for deliberately driving a 1980s car partly for paranoia about this kind of thing..
Between smart cars with telemetry and microphones and the potential for exploding pagers and other electronic devices, there will soon be a general distrust of any kind of manufactured device.
If I had a modern car I would be reading up on how to disconnect the telemetry and take it offline and then get some kind of RF wand to verify that nothing was transmitting. Pleased I don't have to bother with that..
Checking for RF or checking for explosives, which are hard to find apparently, sounds like a small industry might need to emerge to save us from this devilry..
Because I do not have confirmation yet as to what kind of transmitters are being used in the new installs of modern cars, to play it safe, there are two types of transmitting devices you will need to use a RF wand to detect. Some are in a transient mode and remain active at all times and can be scanned for even when the car is off and parked. Others, like trackers used by security teams and law enforcement agencies, only activate when the car is in motion due to its built-in sensors.. There is a real easy way to do this with two people, you have one person walk around the car and wand the entire chassis while you have it going slowly on a driveway, and scanning for all other devices you can do it yourself while parked.
The knowns are what you can get from the car manufacturers. Telematics and remote tracking in packages like On Star, Ford SYNC, etc. Stay away from vehicles with the keyless fobs, they're all RFID, easily exploitable through relays. With a little device that costs no more than $600 you can steal everyone's car provided you know how to use pentoo linux to interface with said device.
One of the newer threats is V2X communication, meaning cars "talking" to other cars, all part of the IoTs never-ending expansion. The issue that causes this is the embedded modems that come in all new cars with 4G LTE and 5G that are constantly connected to the internet.
Right now removing the telematics and the modems only will void warranties in some makes and models, but in the future I have no doubt they will interface this with a kill switch or some kind of self-sabotage of the engine or critical components that would then render the car undrivable without it. All one has to do is study circuitry and learn how to wire and solder, and if you bridge the gap that the telematics component filled before you turn the car back on, even a failsafe trap emplaced within the car would not trigger. I suspect they would attempt to override this at some point with a coded interface which would then require the driver to know coding in order to rewrite the program executables that keep the car online, and then when dissidents get good at that there will be a network that oversees all cars codes to stop that from happening, so at some point the White man is just going to have to build his own damn car again to avoid the jew traps that keep escalating.
It is rare but there are people who can conduct professional security audits of your car to scan for more hidden transmitters. We must all embark on a higher learning curve if we haven't done so already to stay ahead in this game.