Will the EV-Auto mode drain the battery all the way down if you drive far enough ?

Unlike @mr88cet, I see considerable difference in efficiency between normal and eco in EV mode when driving at lower speeds. I can set the throttle to a much more precise power point at low speeds in eco mode and that often lets me keep the m/kWh indicator at around 10 m/kWh at those lower speeds. It's way twitchier in normal and way way twitchier in power mode. At highway speeds, it's not much of a factor since you're more in the middle of the throttle range. So, I just leave it in eco and the cruise control knows what to do.

 

Good stuff! I have also seen these sorts of concerns and effects. For me at least, the differences between Eco and Power mode (in EV) have been fairly small — perhaps on the same order as air conditioner on vs. off.

As with so many things, it depends upon driving conditions: I usually drive in suburban traffic, so I’m only occasionally in a position to be able to take much advantage of Power Mode, or even Normal Mode, anyway. So, I generally keep it in Eco anyway, unless I have a merging kind of situation to deal with.

 

Yeah. ECO mode doesn't reduce the car's ability to accelerate. It just takes more pedal travel to get the same response until you start getting close to WOT.

 

It just remaps the throttle so it feels peppier at low pedal travel. This is an old picture, but it should be very similar in the newer generation. At least it feels like it. Full power is the same in any mode.

 

I think sometime back in 2018, about a year or so after we bought our P.Prime, I did an acceleration study, flooring it in Eco, Normal, and Power modes, and didn’t see much difference, if any. As you pointed out, it’s much more about what it does with the throttle in the middle than all the way “floored” or all the way off.

The mathematical analogy I came up with at the time for the throttle mapping is that it’s more or less like y = x vs. y = x ^ 2 vs. y = sqrt (x):
* Foot off the pedal means 0 power no matter the Mode setting. For x = 0: x = x^2 = sqrt(x) = 0.
* Pedal floored means full power (1), no matter the Mode. For x = 1: x = x^2 = sqrt(x) = 1.
So:
* Normal Mode is roughly linear: the pedal half-way down (0.5) gives you about half the power.
* Eco Mode is (perhaps ironically) like x-squared: the pedal halfway down gives 0.5 * 0.5 = 0.25 power.
* Power Mode is (again, perhaps ironically) like square-root-of-x: the pedal halfway down gives you square-root of 1/2, 0.7071..., power.

Anyway, I’ve more recently concluded that there are slight time- or speed-related effects too: EV Eco Mode also seems to slightly, implicitly “ease off the hammer,” so to speak, as your speed increases. Whereas Power Mode tends to continue accelerating more at higher speeds.

 

No problem. You ask good questions. You could switch back & forth as you described. And that would be fine. There is no universal "best." Your idea might be best if you want a combination of maximum efficiency around town with a more "normal" response on the highway. For me, I just leave it in ECO. Once my foot adapted to the feel of the throttle, there was no reason to change the setting anymore. But I do change the climate control in and out of its ECO mode depending on passengers and weather.

Coming from the realm of sport touring motorcycles, I have not ever experienced a car that had anything like a responsive throttle. They are out there, but cost too many years worth of paychecks. I just like efficiency.

 

I agree on all of these comments.

In terms of acceleration, I have more concerns with HV Mode than with EV Mode! EV acceleration responds instantly, and is more substantial from a stop or near-stop.

Two or three times now, I’ve switched lanes into a faster-moving lane, being used to it leaping over and accelerating quickly. That, only to forget that I’m in HV Mode, where the acceleration has a slight lag and is a bit sluggish from a near stop, compared to EV Mode.

 

Yup! Electric motors have full torque from zero RPM.

But it also seems like at about any speed, if I switch from HV to EV while keeping the throttle in the same position, there's a little extra push like a weak turbo charger kicked in. Going the other way, the speed drops. The only guess I have on that is that they didn't quite get the throttle mapping to match between the two power sources. Not a surprise when you consider how differently they behave.

 

I was about to add something to that effect; you beat me to it.

More specifically, at medium-throttle, Eco Mode especially, switching from EV to HV, everything becomes sluggish. Then switching back to EV, every feels like gliding on Teflon again: quicker, smoother, and slicker!

However, in HV Power mode, I do find the acceleration from a stop to be considerably more responsive than in HV Eco mode.

Soooo, if you need a burst of acceleration, temporarily switch to power mode is usually not a bad idea. Except that you’re more likely to lose tire grip entirely in Power-Mode acceleration from a stop!

As you can tell, it’s a topic we love to ramble on about!

 

Indeed!

This video cracks me up! My favorites:
* Hey, where’d my torque go?!
* What’s with the [engine] noise?
* Transmissions?! What the frack?!

 

What lower speeds are those? I'm rarely getting close to 10m/kWh even at slow speeds.

 

Oh, maybe 25 mph or so. Generally on those annoying speed bump roads found in expensive neighborhoods. On a 35 mph road, I can set the cruise & it'll run along at about 7-8 m/kWh. I can also do that w/o the cruise, but it's more work.

 

Can I switch modes while my phev 2020 is moving (silly Q). It appears The hv mode will only work when the the car is charged? Correct? I’m trying to get the most from a charge.

 

Of course.

No, HV works all the time. EV has to have some EV range showing which can come from the wall, from using charge mode, or from going down a mountain. If you don't have EV range available and try to put it into EV, it beeps, says you can't do that, and delivers a mild shock through the driver's seat. (I might have made up that last part. )

Sounds like you haven't been properly introduced to your owners manual. For most cars, it's basically a kneeling pad for when you change a tire. For the Prime, it's your new best friend. It really helps to peruse that thing till you get an idea what's going on with this amazing machine. That and the old saying around here: "Just drive it." Enjoy the wonderful car. It's amazingly carefree. But it does have lots of cool features that the manual will help you find and use.