You can install a disk in your car, which I would call, then, a flywheel, And you can convert the gravitational potential energy.
可以在车内装个圆盘，可以称之为飞轮，可以转化，重力势能。
2
Each disk is processed or ground to mold, and assembled into a flywheel with a large axial thickness, thereby storing several kilowatt-hours or more energy.