Unfortunately with our phones, OSes, thermostats, doorbells, cameras, PCs, TVs, electric scooters, fans and cars, there is always a way for a manufacturer to find, command and control any of their products remotely even after you paid for it.
So no. It still isn't 'yours' until you can completely and fully control it. That means no backdoors or automatic updates behind your back even after you turn them off.
So doing to cars what's already been done to digital media. Well, I expect there to be a similar response by those technically inclined. Eg. Tesla crackers.
That's assuming they managed to achieve full autonomous driving and got through the legal barriers to this.
