It's easy to say where the line is right now, but you imply that at some point "intent" might be usurped by the computer. I don't think there's any clear way to define that limit. If the driver merely tells the computer where to go ("the 7/11 on 4th Street") and the car does the rest, does that cross the line? Does that usurp the "core human task of driving?" You are ready to let computers calculate the most efficient way to brake, and I am ready to let them do much more, as soon as the technology is available and reliable. Where is there a clear line in between?
Well it seems clear to me that the "core human task of driving" is the supplying of inputs to the 3 major controls: brake, accelerator and steering wheel (5 if we include clutch and gear selector). I'm not necessarily agreeing with kirse, just saying that the line is well defined.
Adaptive cruise control (and even regular cruise control) definitely crosses the line and is available today in a bunch of mass market vehicles.
