Automobile Traffic Trains

Now that Prius III (they call it Prius 2010 in US) and some other new cars has the Lane Keep Assist (Wiki), Pre Collision System (Wiki) and Dynamic Radar Cruise Control why not combining them into a Active Dynamic Traffic Follow up System which would allow the driver to snore (joking) while driving as GPS navigation will know the route, LKA will keep your car straight and DRCC will make sure you follow the car in front of you?
Many cars equipped with Active Dynamic Traffic Follow up System would be chaining to each other, switch the lanes automatically (Blind Spot Assist) and get you to your destination without your effort.

This system doesn't require a lot of investment into the highway infrastructure itself, the road remains passive. It raises the safeness of the driving a lot - no risky maneuverers, it will keep the safe distance in all circumstances and will react in a split second instead of 1.5 seconds human reaction time.
One important thing to note: there must be a loud buzzer to wake the driver (can he be called a driver still?) when approaching the highway exit ;-).
It doesn't seem like a lot of work to me, all the components exist already - they only need to be combined in a central car computer.