Can you not just physically disconnect or shield the network antenna (assuming you own the car outright, i suppose if it's financed it might be trickier to do that legally)?
The same pipe that exfiltrates tracking data is bringing in the data for all the connected features of your car. That would include things like satellite radio, onboard navigation/GPS, software updates/recalls, and concierge/safety services (e.g. OnStar). In some cases, the same data is being used to both track you and provide the service, because the collection is happening somewhere on the backend. I wouldn't be surprised if many cars eventually broke in strange ways or displayed dashboard errors when you did this. The network connection is a pretty fundamental part of the vehicle software architecture and a lot of things depend on it.
If you're lucky enough that your car can continue indefinitely without a network connection, it's possible that you wouldn't notice these features being gone. Realistically though, most people would. The solution here needs to be legislative action to protect consumer privacy. Technological solutions fall short.
The network connection is a pretty fundamental part of the vehicle software architecture and a lot of things depend on it.
Which is very worrying when you stop and think about it. If anything that actually matters is reliant on anything not travelling with you then that can not be a good sign for the safety and security of the vehicle. For one thing any vehicle that has any open incoming connectivity of any kind immediately has an attack vector for malware. And in this case that could literally be a matter of life and death and it could literally be used to attack thousands or even millions of vehicles simultaneously.
The closest I can think of to any legitimate phone home feature is an automatic emergency call function that is triggered by a collision or theft being detected. But of course it's very easy to specify that those features may only be activated from the vehicle side and may only be used to contact emergency services.
Anything else like GPS or infotainment does not need to be integrated at all with the essential vehicle systems or emergency communications functions and can be subject to the usual safeguards like any other device - including an off switch if the owner chooses not to use it and requirements to opt in for any potentially intrusive behaviour.
I should clarify that when I say it's a fundamental part of the architecture, I don't mean in the sense that it becomes unsafe or nonfunctional in the absence of one. Rather, I mean that it's a fundamental communication mode you have to consider when engineering a vehicle, just like cellular internet is a fundamental consideration for mobile OS architecture despite the existence of airplane mode. Hardware is selected in part to support the feature, storage is chosen to support log retention goals assuming periodic offloading, etc.
Whether it's unsafe, or a potential security vector, or has any number of other undesirable properties will depend on the specifics. Every vehicle is a highly heterogeneous distributed system, so the systems I've had a hand in designing may look very different than a different platform within the same company, let alone a different manufacturer.
But yes, every vehicle should remain safe without a network connection and privacy should be not only available, but the default.
If you're lucky enough that your car can continue indefinitely without a network connection, it's possible that you wouldn't notice these features being gone. Realistically though, most people would. The solution here needs to be legislative action to protect consumer privacy. Technological solutions fall short.