Electric

What is one-pedal driving, and how does it work in an EV?

Tesla modal 3 has one pedal driving

Bruce Newton

Posted February 02, 2023

There’s plenty of new terms to learn when it comes to electric vehicles, and one of the most potentially misleading is 'one-pedal driving'.

‘One-pedal driving’ doesn’t mean there’s only one pedal in the footwell of your shiny new electric vehicle (EV). 

What it does mean is the capability of electric vehicles – and to some extent plug-in hybrid and hybrid vehicles – offer to use only the accelerator pedal for both speeding up and slowing down.

Just like normal, you press the accelerator to go, but when you reduce the pressure on the accelerator or lift your foot off altogether, the vehicle will slow and even pull up to a complete stop without you having to press the brake.

This effect happens because the e-motor changes from expending electricity when the accelerator is applied to regenerating electricity for storage while braking. Because of this,  they are often called motor-generators.

Think of it this way: when you’re accelerating - the motor is driving the wheels, when you lift off - the wheels are driving the generator.

What is regenerative braking?

A traditional internal combustion engine (ICE), as used by most cars on the roads today, converts the heat released by burning fuel into motion.

When the vehicle slows down, that motion is converted into heat, mainly by the brakes, and simply lost.

Electric vehicle motors feed electricity both ways. Regenerative braking is a direct result of this functionality, and one-pedal driving dials it up to maximum.  

Engineers estimate that regenerative braking accounts for about 20 per cent of the total driving range of an EV. Regenerative braking is particularly helpful to EVs in stop-and-go city driving.

There’s another handy benefit too, and that’s reduced friction brake disc and pad wear, which in turn contributes to reduced maintenance costs for an EV compared to an ICE vehicle.

The BMW i3

The BMW i3 supports one-pedal driving. 

How does one-pedal braking work?

Different car companies approach driver interaction with regenerative braking and one-pedal driving in very different ways.

Some like to maximise the experience and the effect, emphasising this point of difference with ICE drivetrains. Others minimise it, seeking to make the transition from ICE to EV as seamless and simple as possible.

The BMW i3 - one of the earliest mass-produced modern EVs - is from the in-your-face school of thinking. Motoring about using one pedal virtually anywhere is very possible (once you acclimatise).

The Porsche Taycan, by contrast, does not offer complete one-pedal driving at all. Instead, the effect of the regenerative brakes can be adjusted via a dial to suit the drivers' preference and environment. If the friction brakes are selected to do the bulk of the work, the driver will get a more traditional braking feel, but at the cost of power regeneration.

One of the most accessible systems is offered by the new Hyundai Ioniq 5 (Hyundai call it i-pedal), which allows adjustment of the regen effect and one-pedal driving brake reaction sensitivity via paddles on the steering wheel.

 

Hyundai Ioniq 5

The regenerative braking in the Hyundai Ioniq 5 is called 'i-pedal'. 

How does one-pedal driving feel?

If you’re scratching your head a bit thinking that your ICE vehicle slows down when you release the accelerator pedal too, understand the process is much more pronounced in your EV.

The best place to get your head around this is in an empty car park, where you can adjust the levels of regen and one-pedal assistance to get a feel for what sort of braking works for you.

For many EVs on the market, a quick lift off the pedal should also bring a stronger response than gradually releasing it. After a little bit of practice, you should get to the point where you know the amount of pressure you need to lift to slow for a corner, versus pulling up to a  complete halt.

It should also become apparent after a little experimentation that one-pedal driving is of greater benefit in suburbia than out on the open road.

Like any other part of driving a car – ICE or EV – one pedal driving becomes a skill to perfect. 

It’s especially worthy if you’re into what’s called ‘hyper-miling’, which is extending your EVs range as far as possible between battery recharges.

Usually there is a gauge on the dashboard showing where electricity is flowing to and from, giving you a clue of what driving methods work and don’t work. Considering how long it can take to recharge an EV, it’s a very good reason to give one-pedal driving a crack.

Having said all that, you won’t eliminate the use of friction brakes altogether. In some situations – like an emergency stop – you’ll still want to hit the brakes. Of course, your car’s sophisticated driver assistance systems will sometimes take the decision out of your hands and brake for you.

When you do use both regenerative brakes and the pedal at the same time, you may notice a wooden feeling. That’s common, and indicative of the sophisticated control software working in the background to meld the two systems.

It’s a reminder of just how complex EVs are. 

 

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