One-Pedal Driving Explained
energy.gov
energy.gov
One pedal driving allows us fine motor control without a drastic switch. The regenerative braking also encourages us to not over-brake (you grow to love the idea that you are recapturing energy and avoiding wear on the pads).
In my 2016 Subaru BRZ (manual transmission), cruise control would never apply brakes, so if the hill was steep enough that engine breaking was slowing the car, then it could potentially exceed the cruise speed. But it would need a nearly 10% grade to do that in 6th gear at 60 mph.
Leaving space in fronto of you and trying to keep a constant speed also reduces this effect, this is ironically most used in 3-pedal driving as otherwise you’ll need to go into first gear when hitting a complete stop.
I would like to see some sources on that claim. Or some reasoning.
The thing is I live in one of the cities with the longest commute distances and I’ve spent a lot of time in stop and go traffic thinking about this exact thing. I used to think as you do. I would focus on a truck in the traffic far ahead of me and try to use it to maintain a constant speed at the average of the highway speed. in my experience it creates this laggy elastic effect that probably doesn’t help.
Recently I heard that you should try to maintain an equal distance between the car in front of you and the one behind you, and I think this actually works better (obviously this is my anecdotal experience)
Of course safety comes first always
Speeding up and slowing down causes an accordian effect that results in slower speeds for everyone. The time it takes to reduce speed or stop, then recover to a higher speed is higher than just cruising at a middle speed.
The one pedal driving can be used with an IC car too in certain conditions, just leaving more room ahead.
When getting off the brake the cars are already rolling a little bit before the move to the accelerator pedal and the effect is compounding.
This shows that the small latencies do add up.
This isn't really a problem that other EVs have had. The brake lights come on when you slow down, just as if you had used the brake pedal. It's mostly as easy as triggering at a certain amount of kW generated.
Yes. I watched that Tech Connections video a while back. In that implementation, his car would slow down too quickly without brake lights. I think it would get down to something like 15 mph from 55 before they'd come on, yet the deceleration was at least as rapid as casual braking.
I agree with the Tech Connections example; I have no comment on other EVs.
lol. my definition of "correctly" differs from tesla (and probably the engineering groups that recommend this).
I think it should be a setting so that you can make it come on only when you touch the brake pedal.
on twisty roads, this is especially annoying.
You are basically crying wolf, and other drivers will be desensitized to your brake lights, possibly when you really use them.
Perhaps a better version of your complaint is that Tesla has made the threshold for the brake lights too sensitive; but I would be curious how much observation went into drawing that conclusion.
Thinking it's more dangerous is odd as it's a great example of fail safe.
I think you misunderstand, or just don't understand at all, how regenerative braking or one-pedal driving works.
Manual transmissions (and sport shifting automatics) of most cars from 1904-2024 of sports coupes to trucks don't illuminate the brake lights when engine braking. Drivers following cars should be basing most decisions based on relative speed based on these existing.
If you were to follow behind me in my 2004 manual sports car or a 2021 automatic and only applied brakes when I did, you'd be speeding in my neighborhood and rear ending me, as I keep both in second gear and it keeps me at 20mph.
But really, there should just be a standard - it seems obvious and easy for EVs to get it right: If deceleration is > X m/s^2, then brake lights are on.
I quickly learned to force the break lights and started to follow this issue closely. That's how I became aware of the number.
How the EU saddled for 1.3 and not 1.2 or 1.4 is beyond my knowledge.
It never occurred to me that I might want my ICE to do the same, but I suppose it would be helpful if I'm heading downhill and downshift without touching the brake.
> Brake lights on your electric car will automatically illuminate when you decelerate the vehicle and will remain on when the vehicle fully stops.
Mmmm, nothing better than a dark, rainy evening in November in a city after a long day at work and you're stuck for minutes on end right behind a car with red lights burning into your retinas. Wankers.
Thanks engineer bastards.
Energy from going downhill (assuming it's steep enough to overcome drag and rolling resistance) can go into either of two places: increased speed or charging your battery. The only difference compared to an ICE is that you only get the first option when going downhill (or wasting it into heat via the brakes).
I would still want to be able to respond equally quickly in an EV, but it seems like it would lurch quite a bit if I did the same in a one-pedal setup?
I don't know that I'd want a full toggle in an inaccessible spot to be able to coast. Do any EVs have like a paddle to coast/disable regenerative braking?
In a traditional (automatic, anyway) car, there is one way to brake. You brake lightly if you want to brake lightly, and you brake harder to stop faster.
In a one-pedal EV, you lighten up on the accelerator to slow down a bit, and you remove your foot entirely and put it somewhere else to stop faster.
I would love to see NTSB or a similar group do actual simulator studies to see how normal people react.
Left-foot braking is unpopular outside of racing but only takes about a day to get used to. For the use case you're describing it's probably even less since you'd probably only use it if you need maximum braking in an emergency.
I’ve never heard of collision detection priming the accelerator to apply the mechanical brakes when a foot is removed.
And I've definitely experienced it happen. I've lightly touched the brake pedal with AEB warnings going off and it really slammed on the brakes.
Either way I imagine neither of us has any hard numbers to actually back up either driving style. I'm just pointing out there's no lag to regen braking and in many cars it can be pretty heavy braking.
It's actually entirely possible to both drive at a safe speed and even still want to be able to brake quickly when you see potential hazards on the road.
It might be nicer to have a more gradual slope around the middle.
Sort of like how steering wheels have a little play for comfort.
Also, some people are TERRIBLE at modulating the accelerator pedal.
I was in the car with one of those people when newly trying an electric can and I got queasy pretty quickly.
Maintaining a constant speed on a flat highway isn't hard, but doing it on terrain that goes up and down a lot is much harder in an EV. Maybe it's because every car I've driven before was a manual, but I got really in tune with judging my speed based on my car's engine sound. The visual change going from 60 mph to 70 mph because you started going downhill is not nearly as obvious as the change in engine note as the RPMs rise.
Going through the hills on I-5 near the Oregon/California border, cruise control is an absolute MUST in an EV.
Edit: While coasting might be more efficient than braking, regen braking is probably more efficient than using brakes. (Which might explain the overall efficiency improvement when using one-pedal driving even if we assume coasting is more efficient than braking)
My wife uses traditional driving in my EV, I use single pedal. While she's pretty good at keeping it in the regen-only braking zone, pressing just slightly too hard will end up having some percentage go to friction brakes. I just never touch the brake pedal, so I never engage the friction brakes.
Also known as "fun".
When I drive an ICE, I drive like I don't have a brake pedal because it's an evil device that converts cash into heat and brake dust. The light ahead turned red? Take the foot off the gas. No sense maintaining speed if I'm just going to stop. Driving through a large dip? Let the car speed up as you go down so you'll give yourself momentum to climb out.
It blows my mind when I see someone driving up hill, notice they're going too fast, and they hit the brakes rather than just let gravity do the job.
My previous car was a Subaru BRZ, stickered at 24 mpg city, 30 mpg highway. I averaged 33 mpg. I didn't even drive slow. I just made sure that speed was never wasted unnecessarily.
Letting off the pedal gives an easy way to explicitly command "torque sleep"[1] on the motor, which saves even more energy.
[0] https://cars.usnews.com/cars-trucks/features/porsche-says-no...
[1] https://teslaowner.wordpress.com/2015/10/19/7-0-torque-sleep...
I suppose the system could be designed to detect a user suddenly putting a death grip on the paddle brake and apply the foot brake automatically.
And 152 instances of "brak"(e/ing), at least that's a better ratio than reddit.
If I tap the brake and it doesn't really change my speed, it still signals to those behind that I was (for whatever reason) think about slowing down, which is useful information.
So I think brake lights should come on when deceleration is greater than a certain value, OR when the brake pedal is pushed.
The thing I do most when driving is maintain the same speed, and doing that with one pedal driving is a little hard on my leg, since you have to keep the pedal at just the right angle. I’d prefer a “sailing” mode where one pedal accelerates, the other decelerates, and if you do neither then it just maintains your velocity.
The Tesla already disconnects the pedal inputs from what’s happening since I have the setting turned on for it to maintain one-pedal deceleration when regen is low, by adding in brake. I’d like to continue heading in the drive by wire direction.
Cruise control? If I'm keeping the same speed for more than like 5ish minutes I usually just turn on cruise control. So many cars have adaptive cruise control, and it often works in traffic pretty well. Many cars even handle stop and go in adaptive cruise as well. Both of my cars even let you set it digitally from the steering wheel, so I can accurately change my speed without touching any pedals at all.
Does any car work like that?
It seems dangerous: It defaults to powering the wheels, even if the driver is doing nothing - even when the driver is incapacitated.
I think the newer teslas have three settings - one that coasts, one that has regen, and one with regen + brakes
the last one makes driving the car sort of convenient around town, but it also feels kind of sluggish since when you let off it will bog down.
When I first got it, one-pedal driving wasn't implemented yet. Regen had a "low" and "high", and at first, I used "low", but found myself still using the foot brake to decelerate from high speeds. I change it to "high" after only a week or two, and it became exceptionally rare for me to use the foot brake.
It doesn't feel sluggish at all. You just have to get used to maintaining constant throttle input unless you want to stop. It's a bit of a retraining, but I learned it quickly.
Maybe it's because my previous cars were both manual transmissions which will always apply engine braking, especially in lower gears, so I was used to merely reducing throttle instead of completely removing it when I wanted to slow down a bit.
I drove a recent model 3, it had another setting. I had to look it up since I don't own a model 3.
there is actually:
Regenerative Braking: [Low] [High]
Stopping Mode: [Creep] [Roll] [Hold]
I think one-pedal driving is basically [High] + [Hold] and makes the car feel sluggish
To me, what makes a car feel sluggish is...well...being sluggish and having no power. Since I have the Model 3 Performance, that's not a problem at all. :-D
I switched to using OPD and I can't imagine going back. When I was younger, I drove only manual transmission cars and liked the feeling of being integrated with the car that shifting gears gave me. In the US, that's left hand on the wheel, right hand on the gear knob, left foot on the clutch, and right foot on the gas or brake.
At the time, I believed that only people using a manual were "drivers", everybody else was a "steerer". OPD only uses one foot and one or two hands on the wheel but for me, the feeling is somewhat similar to the manual as the car reacts quickly to my right foot.
I use adaptive cruise control a lot, even on city streets. My ICE cars would not let me set cruise control below 25MPH but the Bolt lets me set it at anything I want. That (presumably) gets me around the issue of not being able to coast - on cruise control, the car will coast when it wants, accelerates when it wants, use re-gen when it wants.
With a manual, I can accelerate, maintain my speed, coast in neutral, brake, use my transmission to slow down, or modulate low speeds with the clutch partially engaged.
I still drive a manual transmission car, but don't mind the one-pedal if I were to switch to an EV.
https://www.roadandtrack.com/new-cars/car-technology/a329586...
Where my manual would stall, my electric comes to a gentle stop.
You also don't get the same sort of "neutral" feeling. You can get close, but it's not like shifting to neutral and taking both feet off the pedals and coasting. You have to simulate it with your foot and pedal position. It becomes second nature, but it is a difference.
Aside from that, it's the same to me. My right foot can still come all the way off the pedal and apply more braking, just like it would if I were engine braking and needed more. I feel fully in control.
Was there an engineering challenge? A safety concern? Do they think that using a single pedal has enough innate advantage that it overcomes the disadvantage of having to be learned? And if so, what's the innate advantage?
Regeneration level is different depending on battery charge and temperature, and it is easier to adapt to this on the accelerator pedal.
Blending between regeneration and brakes is just about impossible to get right - it will be non-linear and make you worse at braking.
Upthread there are several examples of brake lights not going on when people expect, or the regen braking being hard to get to feel right. All new systems are going to be buggy or whatever for a while, varying from model to model. I just haven't heard why putting regen on the brake pedal is uniquely difficult.
> and it is easier to adapt to this on the accelerator pedal....Blending between regeneration and brakes is just about impossible to get right - it will be non-linear and make you worse at braking.
Why?
Light brake pedal action would sometimes brake MORE than expected. Sometimes it would brake LESS than expected.
This doesn't help with the millisecond response you need with your brakes to stop where you want with the force you want.
For me, the learning period would be best measured in minutes. It feels extremely natural. When I bought my Bolt I turned on One-pedal mode and I haven't turned it off a single time.
Today's cars have loads of technological regressions -- touchscreen head units, expensive proprietary headlights, removal of 3.5mm audio input, telemetry -- but one-pedal driving is very clearly a progression as far as I'm concerned.
It already works exactly like this. It's called "blended braking".
One pedal driving is a different feature. It's intended to get even more regen, by encouraging more gradual deceleration. If your habit is to already avoid hard braking, then it doesn't really increase efficiency because you'll get the same benefit from the brake pedal.
I routinely downshift the automatic transmission going downhill on twisty roads or in parking lots, and it definitely provides compression braking when your foot comes off of the accelerator, without touching the brake. I taught my adult spouse to drive and one of the ways I tempered hesitancy was to have her shift the automatic transmission to a lower gear (but not so low she'd over rev the engine driving the speed limit). I was less concerned with fuel efficiency or whether she sounded like a hot rodder than I was with providing her positive control over speed. I'd say it worked. Mostly now she only downshifts going down hill or in parking lots.
One could just as easily (ok it’d be slightly harder) design a system that behaves just like a traditional ICE vehicle while still regenerating the exact same amount of energy.
Any argument for one pedal driving should be centered solely in the UI benefits (less foot movement, etc.) rather than even mentioning regen.
Everything has to allign though for this to feel great. I have tried it with other cars, and it never felt as good.
Just because the EV-brigade gave it a fancy name doesn't mean they invented it. ;-)
The non-electric synonym to regenerative braking is the combined effects of engine braking and/or tyre friction.
I frequently use it myself, for example when I'm approaching a known reduction in speed limit and its safe to do so (in the context of traffic distance behind me) I will disable the cruise control and let the car slow itself down in a relatively short distance.
After a short while you can do that sufficiently accurately so you reach the exact speed limit by the time you reach the sign post.
EV's basically do the same thing. The "regenerative" part is a bit overhyped IMHO it won't magically recharge your battery, maybe add 5–10% over the course of hours if you're lucky with the electron gods. The laws of physics still apply in an EV, unfortunatley.
Yes you might try to argue that EV regenerative braking slows you down faster. But the more aggressive nature is a double-edged sword ... aggressive slowing down with close following traffic, for example, is a recipe for easily avoidable disaster.
1: https://www.energy.gov/energysaver/how-regenerative-brakes-w...
If we are being pedantic about it, yes, you are right in your thoughts and certainly that is what the EV manufacturers want you to think via their marketing.
But the reality is I guess you could say 95% of the "benefit" of regenerative braking is the braking side of things (and so therefore similar to the non-EV equivalent).
There is, without argument, the remaining 5% "benefit" of the generation of electricity. But certainly in my own experience of driving EVs for both long road-trips and short journeys is that the electricity generation is largely manufacturer hype. Why ? Because basic physics dictates that you're playing a net-net zero-sum game ... i.e. what you "generate" you then loose when you next stop at the lights and accelerate again, or when you next overtake a car on the highway or, or, or .... so in the end you might end up with perhaps a 5–10% net gain if you're lucky which isn't really all that much to sing and dance about.
It's not pedantry; you're just taking two roughly analogous things and acting like they have no differences. It IS relevant that EVs call it "regenerative braking" because it does "magically recharge the battery".
> that is what the EV manufacturers want you to think via their marketing.
And yet we're in a thread for an article from the U.S. Department of Energy, not a car manufacturer.
> Because basic physics dictates that you're playing a net-net zero-sum game ... i.e. what you "generate" you then loose when you next stop at the lights and accelerate again
You're missing the point entirely. The point of regenerative braking isn't that it's more efficient than maintaining a constant speed the whole time. It's that it reclaims energy when you would have to stop anyway, traditionally with the brake. i.e. city-driving when you hit stop lights.
A 5-10% net gain is an incredible benefit; I don't know why you're downplaying it. If I could make a 10% improvement to my fuel economy solely by coming to a gentle stop (which I already do anyway) it would be amazing.
No I'm not. I retain my argument that it is a zero-sum game.
The manufacturers would have you believe it's a one-way gain and you can magically recharge to 80% again through regenerative braking, but in the end it almost entirely nets out. So a lot of it is marketing fluff.
That's the point.
> If I could make a 10% improvement to my fuel economy solely by coming to a gentle stop (which I already do anyway) it would be amazing.
For all you know, you probably do.
Its just that your ICE doesn't have some fancy display pumping out the numbers to make you feel all cozy about it.
Why do you think haulage companies spend an inordinate amount of time and money on driver training beyond the obvious parts of the training ? Because driving style can affect fuel economy, sometimes substantially.
You indicate that the generative impact seems trivial, but this is not the case for me. In my PHEV, I get an additional mile of range when I brake regeneratively getting off the freeway. This is non-trivial in a vehicle that only offers about 12 miles of EV range. It's one of the reasons that my average MPG hovers between 90 and 100.
What you describe isn't regenerative braking by any stretch of the definition. Just because one considers "regenerative" to by hype doesn't mean one gets to use the word incorrectly. I guess the flip side of "pedantic" is using a word incorrectly even when one knows it's being used incorrectly.
Most of the rest of the Anglosphere call "gasoline" petrol, and you step on the accelerator. Gas in Australia actually refers to LPG.
When driving on slippery roads, such as ice, slush, or snow.
During a downhill drive.
If you fill your car with heavy baggage or cargo.
I use one-pedal driving downhill all the time. I typically take my foot off the accelerator and hover it more over the brake pedal. Is there a reason this would be unsafe?
Now with autopilot on newer cars as I understand it this is less of an issue but anything with standard cruise control is only gonna work on the interstate most of the time and often not well then.
Are there any EVs that don't have adaptive cruise control?
ACC is becoming a standard feature on ICEs now.
This has been the control scheme for electric skateboards for years.
These EVs are really just large skateboards with over-complicated steering and all the privacy invading tech you could ever dream of.
There's a hill I drive down any time I go downtown. I'll gain 1-2% of my battery back every time I go down it.
> Does the energy exceed the battery capacity?
When that happens, you just don't get any braking and you have to use the foot brake.
> Is it hard to choose the right amount of pedal pressure to maintain appropriate speed?
Can be. The accelerator can be pretty sensitive while going downhill. Just use cruise control, as it'll modulate the regen braking as necessary to maintain a constant speed while going downhill.
In all EVs you can control the intensity real time with your foot. I concede, though, that I have friends whose driving style is best described as "binary" and I imagine they wouldn't be big fans of one-pedal mode.
If 0% throttle is maximum regen braking, and 20% throttle actually keeps you coasting, then...just try using 5-10% throttle. Your throttle is not a binary switch. Handle it with more finesse.