Prius Plug-In Production Car to be Revealed On Press Day 13 Sept

That's too many days left man!

 

I wonder if they'll have any EPA stats to release or if those will wait for LA?

 

7 days left!

 

2 days after 9/11.

 

Any predictions as far as EPA ratings?

 

88MPG - USA (combined)...

 

70 mpge

 

I'm in for 72 MPGE combined

 

The Prius PHV will have a similar EPA rating.

 

EPA does not take EV range into account (otherwise the LEAF would murder the Volt.)

The Prius in EV mode will have less energy consumption than a Volt if for no other reason than its weight -- I guess 10%, meaning an MPG(e) of 105.

MPG(p) will be about 50.

These are guesses of course, that may be wrong for MPG(e) if the EPA uses some sort of blended fuel formula in EV driving.

 

Leaf does beat Volt rather handily (99 mpge vs. 60 mpge combined composite).

The combined composite figure does factor EV range into how to weight the electric and ICE numbers (Volt is 93 mpge electric; 37 mpg gas; and 60 mpge combined composite).

I'm predicting that the PHV comes in well above a Volt with an economy of around 70 mpge. Its just a guess.

 

Do you know how the composite 60 mpge is derived?

 

I think that it uses the J2841 standards to calculate a utility factor (UF), which is the fraction of driving on electric. (I don't know the calculations in detail.) From my reading, it used a traffic survey to give trip length information.

Again from reading the city and highway utility factors can be a bit different.

Once you have the utility factors you use those to combine the CS mpg (city and highway) and CD mpgE and then combine those using the standard 55/45 EPA split.

With a Volt EV mpgE of 93, UF of 0.64 for both city and highway (that's the figure I've seen), CS city 35, CS highway 40 you get

u = UF, e = CD mpgE, c = city CS mpg, h = highway CS mpg
1/(.55*(u/e+(1-u)/c)+.45*(u/e+(1-u)/h)) =
1/(.55*(.64/93+(1-.64)/35)+.45*(.64/93+(1-.64)/40)) = 60.28mpgE.

Your mileage (equivalent) may vary.

For the Prius, city and highway mileage are much better and the CD mpgE should be higher, but throwing some numbers at it suggest that the UF is the key to high composite mpeE. Of course, that's not really a surprise.

 

i think putting a number on it will be a lot harder than most people think... mainly because toyota already said the back can be recharged with regenerative braking and such... a standard prius is good with gas mileage anyway. with the tier we pay in los angeles a volt doesn't come out too much better... in the end while a prius still gets 50mpg baseline (just tossing out a number)

so.. while the volt and the leaf have x amounts of electricity to run on.. a prius will use it all differently. if you never turn on EV till you hit the highway... it's not really using pure EV.. it's torqing out the motor to allow a lot less fuel to be used... or if you use it to accelerate up to 20mph, you lose the worse mpg curve for the ICE...

so.. while MPG will be better... i feel there is no way to really tally it's gas mileage. just a bunch of math that might pan out... a baseline of sorts. (while other cars, you are usually calculating the peak mileage and such)


btw.. anytime you guys mention mpge... you may want to actually toss out a price per kwh... so the rest of the world has an idea of why you are tossing out the numbers you have. our tier is currently 13 cents per kwh... if i were to plug in a car it hits 15 cents for a small amount then it jumps again... charging a car would put it into that tier every month... and that adds up. from what i've read the standard is somewhere around 2 miles per kwh... my prius burns about 9 cents of fuel per mile... at the end of the month the bills are not too much different... except now my house power is dropped into a higher tier which cost me more in the end anyway....

so on a daily (we'll say 40 miles... 2 miles per kwh @ 15 center per kwh)... an electric vehicle would cost ME somewhere around 3 dollars at the end of the day while a prius would cost me 60 cents more. it still boils down to an investment into technology... because the overall cost will probably never make up the difference with gas prices unless they jump again...

a difference of a couple grand over a hundred thousand miles... probably the premium that was paid anyway...

knowing me.. my math is all over... (let the flaming begin)... not saying a plug in is bad.... it's just an investment.. just like my purchase of a genII to help keep the tech going so we can have a genIII... btw... i get this feeling a prius will make better use of each kwh than a volt.. or so we can hope.. because gm sucks at life (did i say that.. i meant... well.. that)

 

UF of 0.64 is high for 35 all electric range (AER) in J2841 graph. In order to get UF=0.64, Volt must have 42 miles AER. The official EPA figure of 35 miles would put the UF at 0.58.



Volt has different number for city and highway MPGe. UF for city should be different than highway since electricity consumption is different (36 vs. 37 kWh/100miles). EPA does not break down the EV city and highway range. To keep it simple let's use the UF of the combined 35 miles range, which is 0.58:

u = UF, ec = city CD mpgE, eh = highway CD mpgE, c = city CS mpg, h = highway CS mpg
1/(.55*(u/ec+(1-u)/c)+.45*(u/eh+(1-u)/h)) =
1/(.55*(.58/95+(1-.58)/35)+.45*(.58/90+(1-.58)/40)) = 56.87 mpgE

Shouldn't Volt be rated as 57 MPGe for the combined composite fuel economy?

I found the alternative UF which takes account of real-world multiple charges per day (J2841 assumed one full charge per day). Even if the Alternative UF is used, Volt must have 40 AER to get 0.64. 35 AER puts aUF at 0.6.

 

Blended PHEV​

I found this sample EPA label for the blended plugin hybrid (like Prius PHV). It appears to be for the bigger plugin hybrid like Ford C-Max Energi with bigger gas engine.



First thing to note is AER=0 miles. Instead the blended fuel economy is 65 MPGe for PHV mode and 41 MPG for the HV mode.

For the blended PHV mode, if you look gas and electricity consumption separately, it got 100 MPG and 17 kWh/100mile. Electricity consumption is very low compared to Volt (36kWh/100mi) or Leaf (34kWh/100mi). That's because gas is used during high power demands.

Another crucial information is the 50 miles for Electricity + Gasoline Driving Range (let's call it EGDR). This would mean it takes 8.5kWh (17kWh/100mi divided by 2) to fully charge the battery.

If we use the J2841 UF, 50 miles would put UF=0.69. Since there is no breakdown for city or highway mpgs, I'll use the same for both.

u = UF, bc = blended city mpgE, bh = blended highway mpgE, c = city CS mpg, h = highway CS mpg
1/(.55*(u/bc+(1-u)/c)+.45*(u/bh+(1-u)/h)) =
1/(.55*(.69/65+(1-.69)/41)+.45*(.69/65+(1-.69)/41)) = 55.02 mpgE

That came very close to Volt's 56.87 mpgE.

Prius PHV​

I want to apply this to the Prius PHV using 51/48 City/Highway CS mpg. For the blended numbers, I'll apply 77% boost indicated from Danny's calculation. To get the UF, the electricity consumption is the key. I'll use 15kWh/100mi since Prius PHV is smaller than the example blended PHEV. With 3.56kWh necessary for a full charge for the prototype, that would put the EGDR to 23.7 miles. The UF come out to 0.425.

u = UF, bc = blended city mpgE, bh = blended highway mpgE, c = city CS mpg, h = highway CS mpg
1/(.55*(u/bc+(1-u)/c)+.45*(u/bh+(1-u)/h)) =
1/(.55*(.425/90+(1-.425)/51)+.45*(.425/85+(1-.425)/48)) = 60.83 mpgE

If we use the Alternate UF graph, UF is 0.5 which puts the combined composite fuel economy to 63.36 mpgE.

 

usbseawolf2000,

Thank you for the research and analysis. I find this stuff very interesting.

If I am reading you correctly you believe the Volt combined composite should be about 57 mpge and the PHV prius about 61 mpge (rounding).

Personally I would be surprised if its not at least 10% better than the Volt so I don't expect anything less than 66 mpge from the EPA.

Although, if the official EPA label for the PHV actual reads:"All Electric Range = 0 miles" that will be priceless.

I do think your sample calculation on the PHV is flawed though. Compared to the sample label your gas consumption in EV mode is going to be around 0.8 gallons per 100 miles (125 mpg) and I think the 15 kwh/100 miles is being a little generous, so I would be shocked if the blended EV mode mpge is rated at 90 for the mpge.

 

Yup, we are on the same page.

If we use 17kWh/100mi, 21 EGDR miles, UF=0.405, it still come out to 60.19 mpge.

 

From what I've read, Prius PHV can complete the City test cycle in pure EV mode. It'll be interesting what the final label would say.

I punched in 125 MPGe and UF=0.405 for 17kWh/100mi and got this:

	Column 1
0	City UF 0.405
1	Highway UF 0.405
2	Blended City 125 MPGe
3	Blended Highway 125 MPGe
4	City 51 MPG
5	Highway 48 MPG
6
7	Combined Composite 65.64 MPGe

I think you are right that the first 21 miles with the PHV battery depleting in the blended mode will increase the MPG above 90. The screenshots posted by John1701a, Paradox and Hills reinforce it since their test drives are much further than 21 miles.