A hybrid vehicle has an internal combustion engine 2 and a flywheel 9. Storage and release of energy by the flywheel 9 is enabled by a continuously variable transmission 10 and clutch 11 under the control of an electronic module 14. The amount of energy transferred from the vehicle one to the flywheel 9 during a deceleration manoeuvre is maximized by increasing the engine speed. As a result, the engine does more work against the braking force of the accelerating flywheel and causes the flywheel to spin up to a higher rotational speed.