A vehicle or watercraft regeneration system includes at least one electric motor capable of generating electricity and a controller for the at least one motor; wherein the controller to optimize the efficiency of the regeneration. The controller can optimize efficiency by including comprises circuitry for biasing the electric motor during regeneration. Also provided is a regeneration system that further comprises an electricity storage device such as a battery, a capacitor, an electrolysis unit that generates hydrogen from water, and a flywheel. In addition, an efficiency enhancing system for a watercraft or vehicle includes at least one electric motor capable of generating electricity; a controller for the at least one motor; and an electrical connection between the at least one motor and the controller, where in the controller adjust one or more magnetic fields of the electric motor during regeneration to optimize the efficiency of the regeneration. Methods for increasing efficiency of regeneration of a watercraft of vehicle powered by at least one electric motor are also disclosed.