Intelligent cars==dumb drivers, IMO. Driving is the legal responsibility of the person in control, and cannot be delegated. Only by having better drivers can there ever be a real solution. Even so, there will be human errors, which we just have to put up with. Depending on technology for safety in motor vehicles is too risky, and successful overrides become unlikely, as the overridee will not be paying attention to what's happening and will take too long to assess and react to crisis. Aircraft have autopilots, ILS etc & pilots, because of the risks of failure in the automated systems and their limited automated coping mechanisms for problems. Cars are not built or maintained to aircraft standards-so I see automated cars as very unlikely as mass transport. The changeover would be difficult, practically/economically. I know there are automated trains but that's a much more constrained medium.