Electric Cars

One Pedal Or Two: A Regenerative Braking Primer

May 15, 2022

A Clever Way To Extend Range

“One pedal driving.” You’ve probably heard the term a few times if you’ve been researching electric vehicles. It doesn’t refer to an electric vehicle actually having one pedal – every EV still has an accelerator and a brake. It refers to the experience of an EV using regenerative braking to slow the car down, often aggressively enough that you might not need to touch the brake pedal.

Regenerative braking helps electric vehicles extend their range. In gasoline vehicles, using the brakes basically just wastes the car’s kinetic energy as you slow down – it’s disposed of in the form of heat generated between the brake pads and rotors. But because electric motors use electrically-charged magnetic coils, they can actually re-capture energy under braking, using the magnetic fields inside the motor to direct energy back into the battery.  

Touch the “brake” pedal, and your EV’s electronics tell instruct the motor to become a generator. The inverted magnetic field simultaneously charges up the car, and generates friction to slow it down. Indeed, in a majority of everyday driving circumstances, an electric vehicle can do almost all of its braking using regenerative braking, only requiring the physical brakes in more extreme situations. Regenerative braking can’t fill the battery back up as quickly as you drain it (hopefully most of the energy you’ve used has been converted into forward motion, moving you towards your destination), it does capture energy that would otherwise be wasted – and adds a few extra miles of range.

Match Your Car To Your Driving Style

Different electric vehicles have different philosophies around regenerative braking. Nissan, whose Leaf was one of the first (and lowest-range) electric vehicles introduced, and Tesla both have fairly aggressive default regeneration, aggressively capturing as much energy as possible when you let off the accelerator. Let go of the “gas” on the highway and it’ll feel like you’ve hit the brakes. Driving in the city with aggressive regeneration feels quite natural, however – you can use the accelerator simply to modulate how hard you want to accelerate or how much braking power you want the car to apply. If most of your driving is done in the city, an EV with more aggressive regen will deliver more range and ease of use.

On the other hand, many German brands, such as Audi, Volkswagen, and Porsche, are much less aggressive by default, preferring to let their cars coast along without regeneration at higher speeds. This may be due to Germany’s legacy of autobahns and high-speed travel: at higher speeds and in the right conditions, a heavy electric vehicle can actually coast for several miles using no energy at all, while losing almost no speed. A combination of the inertia amplified by the weight of the vehicle, and an EV’s typically slippery aerodynamics, means that high-speed coasting can actually increase range more than aggressive regeneration. If you frequently drive at higher speeds, then, you may want to choose an EV that regenerates less aggressively – or at least gives you the option to turn it down.

In the end, the ability to vary how much regeneration is available is the best compromise between the two worlds, and most electric vehicles offer you some form of control. Some, such as the Volkswagen ID.4, only offer two modes (sort of a “city” and “highway,” though the more aggressive setting is marked B for “brake”), while others allow a finer degree of control. Our favorites are vehicles like Hyundai/Kia EVs and the Audi e-tron models, which have paddles on the steering wheel that let the driver immediately access multiple regen levels at the twitch of a finger.

Intelligent Regeneration

As you’re comparing EVs, it’s also worth investigating whether an automatic or intelligent regeneration mode is available. Since many EVs come with advanced driver assistance systems such as active cruise control – as well as built-in navigation systems – they can access these systems to determine what level of regeneration is best in different circumstances. For instance, the Audi e-tron makes use of its forward facing radar, part of its active cruise control system, to measure the distance to the car in front, and can automatically ramp up regen to maintain a safe distance, while also recuperating some additional range. It works brilliantly.

Ultimately, what form of regeneration is best is really going to be determined by your individual driving habits – where you drive, on what kind of roads, and at what speeds – as well as by your individual driving style. Having the ability to control the level of regeneration to suit your circumstances will help maximize your range.