Car Trains?

Reihan Salan posts concerning the future of cars: possibly we'll have car trains: if  the car becomes intelligent enough to travel synchronized with another car, you can imagine trains of 100 cars motoring away at high speeds.  Here's an earlier Discovery post on the idea.  What threw me at first was the idea of how does a car leave such a train, wouldn't the cars behind follow the car leaving the train?   But I suppose you could have an algorithm or a communication method to handle that.  Still strikes me as something I'm too old to adapt to.