You can’t! Even if you don’t use the cell phone based connections the car still has its own systems to wirelessly transmit data out.

You could yank the fuses associated with the cellular antennas but they’re attached to other electrical systems you’d want like the radio in every case I’ve experienced.

Also the data will be locally cached and can be collected when serviced or cause strange failures when it fills up the cars storage space. If considerate, smart engineers designed the car, they’d have different actual systems for the ecu, mcu, tcu and what have you but I’ve encountered one electric where it’s all in one.

So that’s scary.

Don’t buy a car made before 2007 and don’t buy an electric unless you know exactly what you’re doing I guess.

Or treat driving like a surveilled activity you partake of in public.

Just don't connect it to the internet. The radio and Bluetooth do not need an internet connection to work and you can use your phone for maps and music streaming.