Prius Plug-in Hybrid Gets Improved 95 MPGe Rating

Cost of the electricity.

 

Dennis (USB) gets stuff a lot more right than wrong. In this case though, I think he is way under-estimating the wall-to-wheels wh/mile in EV mode. That is, assuming EV mode means no petrol use.

I very much doubt Toyota will have to retract their 15 miles EV/charge statement for the US, particularly since Toyota US officials are giving the statements so close to market release, and Toyota has an enviable record of accurate press releases. Either 'EV' will mean something different than what we assume, or more likely the usable kwh/charge is considerably higher than 3 kwh.

120 wh/km = 193 wh/mile.
If JC-08 is battery-wheels, then wall-wheels is ~ 232 wh/mile.
This works out to 46% more energy/distance in the EPA test cycle than JC-08.

 

I see we differ in the interpretation of history. As I recall, it was based on an formula EPA developed for Plug-ins, but that was never approved. I don't recall seeing an actual formula, but presumed it was a bit like the CAFE standard where alternative energies were (are) mistreated to provide an incentive. (Either that or just measured their usage in some fixed number of UDDS/HWY cycles).


Here are two reports on it..
Chevy Volt 230-mpg forecast dead; feds work on new formula

EPA negs Volt's 230 mpg fuel economy formula | The Car Tech blog - CNET Reviews

 

I'm not sure why this would be a good thing. My guess is toyota has been changing the management software. 49 or 50 is pretty much rounding error. My comment was in relation to getting this "good news" out there fast. Toyota still has 87mpge, 49mpg on their web site. They are probably waiting until they have official numbers before changing it. Why not wait until toyota officially gives us new numbers for the epa including range. Until then 95mpge/50mpg - 15 miles cd range is the best guess.

 

The Prius PHV order site says EV range of [10-15] and speeds up-to 62mph, so the official Toyota statement is probably fine.

 

I'll give you two guesses who supplied the bogus MPG calc to the EPA for consideration. LOL

As for what the calc was based on -- my impression at the time was an attempt to guess what fraction of miles would be EV in a Volt. A BS study from those years (widely circulated on Volt fanboi websites) that 70% of daily travel could be pure EV miles provided the GIGO data input.

 

Btw, ~ 14 miles CD range was pretty typical of the reports given here of beta testers of the PiP.

 

Lets see if I can understand. People in general are willing to spend $30,000 plus on a car, yet at the same time trying to save a $1.

With 15 miles est per charge, u would need 3 charges to spend a gallon of gas at 3.50 rated at 50 mpg. Question is how much will it cost for the 3 charges of electricity.

How many charge discharges on a battery can one get. I think this hype is going way overboard. NOw if u were able like the tesla to achieve almost 300 miles then ok i understand, but 15 -20 miles.

And also the fact that u wont know what the electricity bill is until the end of the month, im good where im at.

If u have the money to invest in solar ( out 2000 plus ) that cost also defeats the purpose of EV.

Just my 2 cents.

 

My guesses would be Argonne NL or NREL, the provide lots of the support for EPA policy formulas...

Agree the % of EV miles was a part of it (then the question is how to count them. For example would it be used the like in this report:
http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=2000_register&docid=00-14446-filed.pdf
where the DOE itself estimated over 300MPG for their examples.


Hmm.. 70% was BS study. Just a coincidence that it just happens to match the real data on voltstats.net and the last time GM released summary data on the full volt fleet covering 20Million miles?

 

Since CD is blended for the PiP, "15 miles EV" could mean "15 miles blended".

 

Maybe, but if this is the case, why would Toyota restrict speeds to below 62 mph ?

 

Absolutely, until toyota tells us the epa numbers we won't know. That is why I said CD (charge depletion) instead of EV. If it is 15 miles non-blended EPA EV, then some facts about the prius phv have changed drastically since the latest press release. Lets just wait for the official numbers, toyota needs to release them before presales become real sales.

 

Sorry for not being clear. Didn't know it'll leave it open for some cheap shots.

Under JC08 cycle, Prius PHV is about 8% more efficient than the Leaf. Ken confirmed 114 Wh/km for Prius PHV and 124 Wh/km for Leaf. That's 184 Wh/mi vs. 200 Wh/mi.

Before going into EPA figures... the production Prius PHV has 4.4 kWh battery. From the Ken's post I referenced above, he also confirmed a full charge requires 3 kWh, which also include the charging loss. EPA takes account of charging loss so this is good.

LEAF is 340 Wh/mile in EPA testing. Toyota says Prius PHV would get 15 electric-only miles. 3,000 Wh / 15 = 200 Wh/mile.

How could they get so low at 200 Wh/mi? The ICE is there to filter out the high drain miles in HV mode, sustaining the SOC point when the ICE started. 200 Wh/mi would give 169 MPGe rating. However with some gas mixed it, I think the total blend drops to 95 MPGe.

 

Yep, coincidence. It was that same study, btw, that prompted GM to size the CD range to 40 miles.

The study did not conclude that a Volt would be driven on average 70% EV, 30% petrol. It found on survey that 70% of the surveyed group's car use during the work-week was less than 40 miles a day.

 

Dennis, I hope you do not think I am throwing out cheap shots.

Earlier someone posted that the PiP managed 26.4 km EV miles in CD mode on JC-08. If the battery-wheels consumption of 114 wh/km is correct, then total CD is 26.4*114 wh = 3 kwh.

So I think one error here is thinking the 3 kwh consumption includes charging losses.

I posted earlier a calc that EPA requires 46% more energy/distance than JC-08. Lets start from 114 wh/km PiP battery-wheels in JC-08 and translate to EPA wall-wheel:

(114 wh/km / 0.62) * 1.46 / .83 = 323 wh/mile.
Where
.62 = miles per km
.83 = charging losses

Clearly something is wrong.

 

Umm if the Ice is filtering out the high drain miles, its not 15 electric-only miles, as that means no gas can be used. EPA's electric only is just that.. once the ice starts is not All-electric range is over.


cannot compare wh/mile in EPA to some other metric where its Wh/easy-mile

 

Perhaps, it always switch to CS mode when the gas engine is running and CD is reserved for EV miles.

 

Can we agree that PiP EPA wall-wheels will be about 315 wh/mile ? This will let us calculate some relative efficiencies for the PiP vs the Volt:

Volt CD/PiP CD: 360/315 = 14% more energy per distance
Volt CS/PiP CS: 50/37 = 35% more energy per distance

See how much clearer that is than the MPG(e) balogna ?

 

Not that clear since it is Volt/prius for one computation and and Prius/Volt for the other.

Can do the MPGe ratios as well. Converte 315 -> 107MPG(e),
107/94 = 14% more efficient per distance (prius is on top for both now..)
And then one does not need to confuse people by swapping numerator and demonator to adjust for the direction of "better".

However, I don't know where you got the 315... that is 116MPG(e), which is yet another number (and one I've not seen quoted before).
So don't know that I'd agree. I'm waiting on the EPA numbers.