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Comment by rladd | Hacker News Reader

Toyota Prius and Prius Prime also charge their batteries during braking, but use the brake pedal to decellerate.

This seems safer to me and also easier to control: you press the brake and it brakes. If it can regen, it regens, if not, it uses the disks. If you hit the brakes hard and the regen won't be enough to slow you down, it will use disk to the extent it needs to (or just switch to disk entirely).

Coasting is also good: no reason to regen if what you really want to do is coast, and no reason to have to keep your foot on the accelerator in that case either.

Prius do regen slightly in coasting mode, but it's not very noticeable.

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The 2nd gen Prius (probably 1st gen too) has a distinct pre-travel during which it only regenerates, and only past a certain point does it apply mechanical brakes.

When the battery is full (after descending a long hill) the pre-travel does nothing at all. Of course there's no engine braking during coasting when the battery is full, so you'll know ahead of time.

On newer models, the pedal behaves in the manner you describe.

> Toyota Prius and Prius Prime also charge their batteries during braking, but use the brake pedal to decellerate.

Well, they actually do regen in Drive with the foot off the pedal; the brake pedal engages traditional brakes (with the regen also). Coasting requires slightly engaging the accelerator.

Prius also has an “engine braking” mode (which actually uses either regen or engine braking, depending on hybrid battery charge state) on the shift lever.

> Prius do regen slightly in coasting mode, but it's not very noticeable

The difference between pedal disengaged regen and pedal engages to coast is quite noticeable.

> Toyota Prius and Prius Prime also charge their batteries during braking, but use the brake pedal to decellerate.

It also makes way more sense: your drivetrain can't be perfectly efficient so being unable to coast (and regen-braking every time you would be) is a double energy loss, first waste energy converting kinetic to electric, then you waste energy again converting back from electric to kinetic.

Regen-braking instead of coasting only makes sense in an "engine braking" analogue: have the car regen-brake to try and keep below some set speed on downhills.

You can turn on full engine-braking in a Prius and it works fairly well (but also uses the ICE). It's enough that I use it entirely in most cases to get down to coasting speeds.

I drove a Toyota CR-V and was really amazed how it manages to burn fuel while decelerating. It is a disgrace of a hybrid vehicle.

Does it actually burn fuel? I've coasted an ICE car down a mountain in the winter and the temperature gauge didn't budge (and thus the heater never warmed up), implying no fuel was used. Surely a hybrid could do the same?

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