This study was all about harnessing lost energy when the vehicle lost speed without reversing the process in an engine. The simplest way is recover this energy without transforming it to another form. For example the kinetic energy of the vehicle can be stored as kinetic energy, to be used again for acceleration. It does not produce perpetual motion because of entropy, but it decreases the energy lost when the vehicle brakes and reduce speed. Instead of releasing energy as heat through the brakes, it is stored in a rotating flywheel.