I dont know about whether it is illegal, but it ought not ever be illegal to hack and change your own vehicle, except for changing things like the engine number and the odometer (i.e., legal requirements from the state).
This sits in the same realm as adblockers for a browser.
> Is it even possible?
the car maker might be able to make this impossible, but last i heard, people have done it. Unfortunately, due to a lot of cars being software, the manufacturer could detect and cause headaches for you, in an attempt to discourage it.
I reckon there ought to be laws, akin to the right to repair laws, that ensures you truly own your car and the manufacturer cannot lock you out.
In many countries it is illegal to change anything with the vehicle without going through a homologation afterwards, unless the parts are already homologated. This happens because it affects security and can be a danger to others and you. The consequences can range from fines to the destruction of the car.
Later that evening: “Five killed in car crash. Evidence points to use of seat heaters without paying subscription fee, thus making the vehicle not suitable for highway commute.”
Authorities care. Yes it's your property and you can do whatever you want with it. The question is whether you're allowed to operate the vehicle on public roads afterwards. Cars go through thorough certification processes (homologation) and that includes software.
Can you prove that your change does not negatively affect a certification-relevant function?
In the United Stated at least, federal law stipulates that modifications only void warranty if they can show that the modifications caused the failure.
My understanding is some dealers, especially BMW are dicks with any ECU tuning and will deny support. And then it's a question of whether it's worth hassle to go to court or eating the cost. Maybe that was just limited to messing with engine/transmission.
This sits in the same realm as adblockers for a browser.
> Is it even possible?
the car maker might be able to make this impossible, but last i heard, people have done it. Unfortunately, due to a lot of cars being software, the manufacturer could detect and cause headaches for you, in an attempt to discourage it.
I reckon there ought to be laws, akin to the right to repair laws, that ensures you truly own your car and the manufacturer cannot lock you out.