If a car has parking assist, cruise control, and is drive by wire with no link between pedals and actual fiddly bits, it can be remotely controlled.
Happy thoughts.
Yes. Even brakes, although mechanical/hydraulic in operation, can be controlled because the anti-lock system puts a link between the brake pedal and the brake pads.
Throw in a non-mechanical ignition system and the car can only be steered. Throttle wide open, brakes disabled, no way to shut it down - yee haw!
Yep. Over the past few years, there have been a few vague comments by automotive engineers to the effect of: "...Yeah, we warned the bean-counters that this was a liability and that more security was needed, at the very least."
In one case, the engineering team already had a security patch designed and ready to implement. Can't recall which manufacturer, but it sort of applies across the board.
I’ve seen a video with experiment where people in the back seat had software that could override the driver side driver so he had no control over his “driving” the car !!!