Understanding Prime Reported MPG With EV Mode Capacity

We do at least get some charge-sustaining figures from the WLTP tests, but like many manufacturers, Toyota don't publicise anything other than the weighted combined figure, at least in Europe. You can see them in the CoC here:

PHEV in Europe - Certificate of Conformity (CoC) | PriusChat

3.6-5.6 l/100km, combined 4.6 l/100km

65-42 mpg(US), combined 51 mpg

 

The OP's issue here is that for a trip done completely in HV mode, the car is deciding to use gird charge during the trip instead of simply keeping the battery SOC at the same point for whatever reason. thus the trip isn't on gasoline only.

 

I was just replying to @GeoJ ........posted in THIS thread

 

No, Predictive Efficient Drive is a different feature, and discussed in the EU owner's manual in a different section than the "Predictive EV Drive", the one @KMO was talking about.

The latter, yes, needs the car navigation system (standard in EU Prius PHEVs) and affects directly the SOC management because it decides autonomously to change from EV to HV mode (even upon the traffic conditions, other than the route features). It needs AUTO EV/HV mode on.

We are all curious to test it, in September the first PHEV will be delivered in EU.

 

Very interesting and a major change relative to gen 4.
I've always thought that, for a long trip, using a small quantity of the charge of the battery to improve FE was the best investment.

 

How much SOC are you guys losing just driving in HV mode? I mean assuming a full charge or at least above the point where it needs to be to be able to switch to EV if desired? I do understand that there is a bottom and upper range Safetynet that Toyota has built-in to the battery and charge infrastructure which is nice.

This is my first PHEV and I’m trying to understand it all (will have the car in a couple weeks). My understanding was that unless you are using EV mode only, the SOC will not deplete and can be “saved” to be used later?

Is there only one big battery for the prime or two? I thought there was only one big battery which held a lot extra in reserve to run the car on EV but switches to HV just like a normal Prius once depleted (or you can switch manually)? Or is there actually two separate batteries one for EV and one for normal HV?

If my understanding is wrong, and it seems to be by reading a couple threads on here, how much on average are people losing charge wise just by driving in HV?

Maybe I’m just overthinking this. My round trip commute to work is pretty much exactly the range that I should be able to get in full EV. Ie. Just plug in daily and enjoy the EV drive and use HV for long trips…

-It’s very possible that I don’t fully understand all the modes yet since I don’t have the car in my possession. I’ve just been reading all the threads and watching all the YouTube videos. I have not yet seen an in-depth YouTube video describing how or when to use each mode appropriately.

 

Oh almost forgot.

Am I correct that the 220 HP will always be on tap no matter what if driving on HV? SOC should not matter at all right? Kind of goes back to my one battery or two battery question. Is the prime just a regular Prius with an extra separate EV only battery or does it just have an even bigger single battery that it pulls from that’s regulated and switches as needed? Sorry for the basic PHEV questions but this will be my first one like I said, and trying to fully understand.

 

Only one traction battery , remember HV can be chosen by you , the car will then decide to operate sometimes in HV and sometimes in EV this will maintain your SOC for future use . Terrain, temperature,speed, will make the car choose modes differently , I prefer highway travel in HV ....finally don't overthink ....just drive it

 

Thanks, this definitely makes sense. Commuting, Running errands, suburban and city driving, dropping the kids off to school, etc = EV prob best for sure.

Well, my commute to work is anywhere from 18 to 21 miles depending which route I take. I can do the suburban route into the city with lots of stoplights, which is actually the shorter distance with probably a lot more regen possible or I can take the highway which I normally do going home which also includes some city and suburban driving at the beginning and end. I guess once I get the car, I can try it in EV and see if it kills the battery coming home on the highway. If not, I can just switch to HV for the 10-14 mile stretch or so of I95, depending on exit I take.

Highway only and long trips = HV.

 

yep ! Enjoy your Prime , I'm shure it will fit your needs ....

 

"Using EV mode only"? "Auto HV/EV" and "EV Mode" both have a strong preference for depleting the EV SOC first rather than burning fuel. (In Europe models with Predictive EV Drive, Auto HV/EV switches to "deplete the EV SOC by the destination").

HV mode is roughly a "hold EV SOC" mode. When in HV mode, whether manually selected or forced, it operates basically like a non-plugin Toyota HSD car - it tries to stays within a <1kWh range of battery charge, using it as a buffer to run the engine efficiently, provide extra power when needed, and capture braking energy.

One reason the SOC charge can vary using HV mode is due to it not maintaining the position of the HV charge range between sessions - on entry to HV mode it looks at the current SOC and chooses a new <1kWh charge range to use for operation. So it can drift for that reason. But on one HV segment, it shouldn't normally drift.

The bounds of the HV region are not totally hard - it will allow the SOC to rise, pushing its HV band up, if it keeps getting regeneration energy on a long downhill, rather than throwing the energy away, like a real small-battery HV. And it's possible it might allow the HV band to drop if you were to sustain high-power demand, rather than losing power like a real small-battery HV.

One big battery. You can do HV anywhere in the range, but it's forced once "EV charge" drops to "--%". That's when you've hit the bottom <1kWh of useable capacity. The "HV range" clamps to the bottom of the overall range. If you did manage to regenerate downhill long enough, you might manage to push SOC back up into having useable EV charge.

For maximum efficiency:

* If it's reasonably likely your trip is within EV range, use EV Mode, then it'll only burn fuel if you don't make it.
* If you know your trip is outside EV range, manually switch between EV Mode and HV Mode - use HV Mode on the highest speed sections. But make sure to use up your EV SOC by the time you get there.
* If you have a Europe model, Auto HV/EV will do the above for you.
* If you have a US model, don't use Auto HV/EV if you want to maximise efficiency, as it's basically the same as EV Mode, but with the ability to run the engine for more power. It doesn't do the "HV mode on fast sections" thing above, cos it still favours using SOC as soon as possible, while EV Mode constrains the power and won't run the engine if you stick your foot down.

220HP will almost always be on tap in Auto HV/EV or HV Mode, even when the EV Charge says "--%". It will only not be there when EV Charge is "--%" and you have also reached the bottom of the HV part of the charge gauge. But the car will try hard not to let the charge get there, like any non-plugin, topping the battery up whenever it has spare power if it gets that low.

 

Excellent and very thorough reply. Thank you for helping me understand.

 

It's all second-hand at this point - my 2023's on order.

But it's what I've managed to collate from the New Car Features docs on Toyota's techinfo site, and manuals, and reports from owners here such as yourself - for 2023 specifically and cross-checking with Europe and US pre-2022 models - noting where there are reports of differences and where there are not.

 

If you are using HV mode and have remaining EV charge, it will slowly deplete it. From other people's comments, this seems to be a change from the 2022 and earlier, but as a 2023 owner, it definitely will use the EV charge albeit very slowly. I haven't personally tested short/long trips and all that, largely because I prefer to use EV mode.

Edit to add:

I had a lot of the same questions about when to use this mode or that, but after driving the car since May including a road trip vacation, I think the best way to use the car is ignore the modes. It'll start in EV and swap over when you run out of charge. Just let it do its thing.

Unless you're doing track day and want that 220hp, then stick it in HV/Sport.

Oh, and it says it has a 600 mile break-in period. I figure most of break-in is the ICE, so I ran a lot in HV when we first got it. Part of that is I knew we were going to be taking a road trip a month and a half after I picked it up and wanted the break-in period over before we got on the highway.

 

Good stuff, I appreciate the input.

Since I have a 250 mile drive home from the dealer once I pick up the car that should take care at least a third if not almost half of the break in period. With it being a CVT I am not worried about the long initial drive because of the constant rev changes that a cvt does. Although if I do decide to use radar cruise control at all, I will vary the speed every now and then for sure. Plus a nice stretch through NYC heading back down 95 should account for some stop n go & Regen

 

So would this not mean that it would make sense to still plug in and fully charge if able, even knowing you will be going on a long road trip or vast majority on HV only.

I mean if the car is pulling from the EV side of the stored battery a little more than it should wouldn’t this mean better mpg across-the-board compared to running with a “depleted EV auto switched over” battery…aka reg Prius style.

 

The 2023 Prime reportedly gets about 40 miles on EV only from a full charge. So my question is, if you're driving on EV mode only, once the EV capacity runs out after passing the 40 mile mark, does that mean you would be driving on gasoline only, without any assist from the hybrid battery, until it's recharged overnight? If so, I would imagine the MPGs would be terrible.