Conventional braking systems reduce speed by converting kinetic energy into thermal energy by generating friction on brake discs rotating with the wheels. The heat energy generated at this time is dispersed into the air and disappears. And the regenerative braking system compensated for this; This is mainly used in electric vehicles, and when deceleration is required, the rotational resistance of the motor is used to reduce the speed of the car, converting kinetic energy into electrical energy and storing it in the battery. The electric motor that generates power acts as a generator that creates electrical energy during deceleration. For reference, most electric cars house a feature that allows the driver to adjust the amount of regenerative braking. Hyundai Motor Group's latest electric vehicle has evolved one step further: a smart regenerative braking system that controls the amount of regenerative braking by itself. An electric vehicle equipped with this system maximizes regenerative braking efficiency and improves fuel economy by about 1.7%.