Abstract: A vehicle has as its prime source of power a fly-wheel (6) that is connected to a driving wheel of the vehicle through a continuously variable transmission mechanism (16). The transmission mechanism comprises conical drive members (53, 54, 82), with a spherical transmission element (55,) 81 between the conical surfaces, to transmit rotary forces from one drive member to the other. In this way rotation energy from the fly-wheel may be transmitted to the drive wheel on acceleration of the vehicle, or transmitted from the drive wheel to the fly-wheel of retardation of the vehicle. The vehicle is for use in a transportation system in which the vehicle travels around a predetermined route, with the fly-wheel being recharged either mechanically or electrically at a vehicle terminus (L).