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Comment by peeters | Hacker News Reader

What was the impetus for manufacturers to design it this way I wonder? It seems to me like you could easily implement regenerative braking in the same way by having the brake pedal respond to light pressure with regenerative braking, and firm pressure with brake pads. Then you don't lose the ability to coast, nobody has to learn anything new, and you don't have to transition from pedal to pedal if you need to surpass the capability of the regenerative brake.

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?

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> It seems to me like you could easily implement regenerative braking in the same way by having the brake pedal respond to light pressure with regenerative braking, and firm pressure with brake pads.

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.

> using a single pedal has enough innate advantage that it overcomes the disadvantage of having to be learned?

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.

Every car with OPD I've been in also had an option for a more typical "coasting" style, where you need to use the brakes. I've been driving cars extensively for 22 years, and picked up one pedal driving during the test drive of my EV. 4 years later with 95% of my miles done using OPD, the urge to smash the brakes is still there if I need to stop quickly. Having said that, I have no idea how new drivers who spend 100% of their time on OPD will handle actually-using-the-brake situations.

Give me an idea of how often you'd hit the brake pedal while trying to use one pedal. A few times an hour? Week? I feel like if it's a regular enough thing the natural impulse would be there for new drivers too, but if it's something you're doing every couple months, probably not.

I'd say, maybe once or twice per hour of driving around town on local roads. Essentially just when someone in front of me brakes hard.

But what's the benefit over peeters's suggestion, which to me seems strictly better?

Some cars do exactly that (put regen on the brake pedal). And they have lots of unexpected behavior and non-linear brake feel.

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.

> And they have lots of unexpected behavior and non-linear brake feel.

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?

I had a car that did this.

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.

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