> By that I use our Nissan Leaf as an example. There is no direct mechanical linkage on any part of the car that makes it stop, go, or steer. Parking brake is electrically actuated. Brakes are run on a wire. "Gas" pedal is wire. I'm pretty sure the steering is drive-by-wire, but I'd have to go back and look it up to make the claim with confidence. I'm sure there are redundancies, but I'm picturing an ECU letting its smoke out and then you might as well just let go of the wheel and pray to your preferred deity.

This is not completely correct: your Leaf does have a purely electronic throttle and the e-brake is actuated by a solenoid, but no production passenger car presently uses brake-by-wire, and the first (and presently only) production passenger car with drive-by-wire is the Infiniti Q50. While your Leaf does have additional electronic braking means to make the regenerative system work, if the ECU lost its magic smoke the service brakes would still work. As to drive-by-wire (perhaps you're confused with electronic assist?), on the Q50 at least there is a physical linkage to the steering in case of electronic failure.