(18)"motor vehicle" means any mechanically propelled vehicle adapted for use upon roads whether the power of propulsion is transmitted thereto from an external or internal source and includes a chassis to which a body has not been attached and a trailer; but does not include a vehicle running upon fixed rails or [a vehicle of a special type adapted for use only in a factory or in any other enclosed premises]; [Substituted by Act 100 of 1956, section 2 (j), for 'used solely upon the premises of the owner' (w.e.f. 16-2-1957).]
