Robert Maxwell wrote:
Central control creates more problems than it solves. Allowing cars to go a lot faster makes little sense because of how energy inefficient it is. Your average car tops out its fuel efficiency around 55 miles an hour, and declines precipitously beyond that point. Cars that can easily go 200mph and do it efficiently aren't even on the drawing board today. You'd have to address that before it makes any sense at all to have central control. As gturner said, there's also a much higher accident risk at such speeds. The only place such high speeds even make sense is intercity/interstate highways, in which case you'd be much better served having high-speed trains instead.
Autonomous self-driving cars exist today and could be a common sight in the next decade or two. Central control of them makes very little sense, though.
I agree that it causes more problems than it solves; that was kind of my point. Self-driving cars are touted as bringing to the table huge improvements in speed, efficiency, and safety. My point was that in order to really see the huge increases people talk about the cars can't be autonomous; they must be coordinated in some way. But, doing so introduces some other serious, probably deal-killing, issues.
Regarding speed, the primary reason that fuel efficiency drops off at higher speeds is because of increases in air resistance. If the cars were traveling at high speeds and very close to one another, that air resistance would be dramatically reduced, and therefore the efficiency penalties for high speeds would be similarly reduced.