Abstract—Hybrid vehicles are becoming increasingly popular as the world become more environmentally conscious. The efficiency of hybrid vehicles is limited by the ability of their electrochemical batteries to absorb large regenerative braking currents. Any energy over what the battery can safely absorb is dissipated through the friction brakes of the vehicle. This work will investigate the use of a dedicated high-power device, specifically an electro-mechanical flywheel, to absorb the excess energy and return it to the vehicle batteries. Both modelling and experimental approaches are utilized to analyze the increase efficiency potential, as well as the ability of the electromechanical flywheel to absorb excess braking energy.