Wired has an article about a self-steering bus system, whereby magnets are embedded in the road and used to guide the bus along its route and into bus stops. Drivers still retain control of accelerations and the brakes, but the author says that they've tested it with automated speed controls and it worked well. The cost savings of guiding the bus along a track is that it allows for buses to pull into and leave stations more quickly (it shaves "seconds" off), and the system is so accurate that the bus ends up only a centimeter from the curb. Apparently these "seconds" and the ability for a bus lane to be ten feet wide instead of the usual twelve make the system "as efficient as light rail lines." This would be in ideal settings – that is, in a dedicated bus lane. I assume the system would work even better if the acceleration and braking were automated, as those are areas where a large vehicle can can fuel efficiency if stopping and starting is more precise strategic than a human can manage (and buses use a lot of gas). While public pressure wouldn't allow vehicles to be driven automatically, eventually costs could also be cut by eliminating the driver (cue labor protests).