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Comment by k8sToGo | Hacker News Reader

Crusing is much more efficient than one pedal driving. So it does not save power at all.

The control scheme has nothing to do with the efficiency of the car. Whether one pedal or two, it’s going to use the same power for the same acceleration/cruise/deceleration profile.

Unless you’re concerned about the energy usage in your ankle when maintaining pressure on the gas with your foot?

It has to do with that your feet or legs are not super accurate machines that can keep the pedal at 0 regen and 0 acceleration for long enough time.

There is a decent sized gap between 0 acceleration and 0 regen equal to the amount of energy required for the vehicle to maintain speed against rolling resistance and air resistance. Anywhere inside that gap, you're not using regenerative braking at all, you're just decelerating from not supplying enough power to maintain speed.

That is not the type of cruising this is referring to. It is the wrong name, to be fair. It really is just letting the car roll.

"Just letting the car roll" results in deceleration, but at a rate chosen by physics rather than you. If deceleration is not what you want, you have to continuously apply power. If it is what you want, it's still almost never going to be at the rate you want, so you still either have to apply some power or apply some braking. In the former case, you're pressing down on the pedal enough that no regenerative braking is happening. In the latter case, regenerative braking is obviously more efficient than friction braking, because the latter has 100% losses to heat.

Controlling the car’s speed is the driver’s primary job. One pedal or two you need to use your right foot to maintain the speed you want.

Coasting with no acceleration or deceleration except that provided by rolling resistance and the road gradient is so unlikely to be the exact acceleration you actually want - there’s no particular value in privileging ‘zero motor power’ as needing to be an easy state to achieve.

If you’re lifting off the throttle enough to activate regen braking, you would be applying the friction brakes in a car as well. Maintaining a steady speed is more efficient than varying speed, but if you have to vary speed then one pedal driving is superior in every way.

If your one pedal driving doesn’t save power, then I would suggest a driver mod.

Yes of course. These are very theoretical discussions anyways. In reality one pedal driving is quite awesome.

You don’t have to use one pedal driving to use regenerative braking in most EVs. They use regenerative braking to effect control inputs on the brake pedal too.

Are there any cars that "cruise" (by which I assume you mean maintain velocity without applying a pedal)? Non-EVs mostly sort of do so, they still slow down gradually. I'd be interested in trying a car that cruises indefinitely. Sort of an automatic, always on cruise control.

Well cursing in an EV is the equivalent of putting an ICE car in neutral. Modern ICE do that as well. To answer your question it still slows down due to wind resistance and friction.

If you put a modern ICE car in neutral while moving, you’ll use as much gas as you would while sitting in a parking lot idling. However if you just coast in gear with the engine braking slowing you down, a modern car will turn off the fuel to the engine, so zero gas is used.

Then you trade greater pumping losses (reducing kinetic energy of the car) in exchange for lesser potential energy (gasoline) usage. It's not a free lunch.

Yes, but driving a vehicle is not a steady state problem. When a driver lifts the throttle, the next action is typically an intentional demand for a loss of potential energy (i.e. the driver is moving their foot to the brake)

On mine it's a driver preference setting - there are a couple of settings like that which I set to "make the drive more ICE-like because I still drive ICE cars occasionally and don't want to be betrayed by developing EV-specific habits" (even though EV "style" driving features, like 1-pedal, are generally more comfortable/relaxing.)

Are you talking about basic cruise control that's been around since forever?

In the 90s I drove a Dodge Spirit from Florida to NY using cruise most of the way - the cruise adjustment was incredibly responsive.

IIRC 10% more effective to be precise. The UX is worth the cost.

I agree. It’s similar to the discussion of saving emergency by not using AC. No thanks.

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