The reason I think this is a bad idea is that it lulls you into a false sense of security. The article makes recommendations that seem thorough and sensible - keyword "seem" - but, as mentioned elsewhere here, there are other potential hidden sources of telemetry (in CarPlay and Android Auto), and who knows what else.

For this kind of thing to succeed as a general lifestyle, you would need to invest an enormous amount of time making potentially irreversible modifications to all kinds of electronic equipment - only to be virtually guaranteed to miss something.

Do this kind of thing if you want, but don't be fooled into thinking you're actually solving the problem for real.

I think you can substantially reduce the information collected about you, without an enormous amount of time. Security - and any solution - isn't about perfection; it's about improving the situation and making attacks more expensive.

Every HN thread is accompanied by comments saying it's all hopeless.

If you disconnect the modem, the car can't share any information by itself. In my opinion, that is a huge win.