Comment by mdp2021

> replace the br[ake]s with some home-grown solution

Funny you mention the brakes, because a friend of mine told me just days ago that he used to change his own brakes consumables (pads) until the new car, which "throws an error" if you replace the part - you have to go to an official service office for the computer configuration.

Now, do not forget that the need for the intervention of third parties lowers the car reliability ("far away", "too expensive", "device too old", "operation failure", "inexperienced operator" etc.).

This should show that your argument has difficult sides. Of course you should be able to act on your critical possessions. It should be within a good framework, but it should be fully, practically possible.