Regenerative brakes are an important part of what makes PHEV and EV cars extra efficient. This type of braking system allows a car’s electric battery to charge while driving when the brakes are used, meaning less energy is wasted when braking and batteries have to be charged less frequently than they might otherwise.
So how do regenerative brakes work? In gasoline cars, when you hit the brakes, the energy it takes to stop the momentum of the car dissipates, which is why we get lower gas mileage in the city than on the freeway, despite that we’re going faster. You’ll notice that PHEV and EV mileage estimates tend to be higher in the city than on the freeway—regenerative braking is why.
Regenerative brakes capture the kinetic energy as the car is slowing down when you brake and funnel it back into the battery, which in turn runs the electric motor. The car’s onboard computer signals the battery to stop using electricity to stop the car and instead to start receiving it as the brakes create momentum.