Officially, it was tested last year in Amsterdam for some 12-mile range. The bus also packs some amazing features like image recognition and so on - reportedly it can recognize traffic lights, steer through tunnels, and can recognize pedestrians and bicyclists.
It is also designed and programmed to detect and pull over at bus stops, where passengers can either embark or disembark the bus. It packs lots of sensors to detect metal, oncoming vehicles, road signs and road markings.
Mercedes is claiming that the Future Bus is also more fuel efficient than your average city bus operated by a human because the City Pilot system is always braking, accelerating and shifting gears to optimize efficiency.