Yes, driverless cars are going to be a nightmare for the environment and the built form of cities. Just as we are hitting the limits of acceptable sprawl now in many cities, they'll enable the next level. Its possible that the driving improvements will counterbalance this (i.e. the cars won't have to stop and accelerate as much, cars on the highway could drive a lot closer and draft each other) I doubt it'll be a net positive.
Well thanks a lot for the nightmare fuel. Ambien sales are sure to increase.