87 MPG(e): Toyota Confuddles PC experts

Even Popular Mechanics (Mar_2011) punted on this exact calculation for the Volt. It is apparently a complex, behind the scenes "tricky sticker" EPA calc (PM's words, not mine). We do however know for Volt 2011 model:

VOLT 2011
MPG (Hybrid) = 37 Combined City+Highway on window sticker
MPGe (EV) = 93 Combined City+ Highway on window sticker
Utility Factor = 58% (of miles typical expected driven in EV mode)
MPGe Combined Composite = 60 MPGe on window sticker

What I think we know for Prius PHV (pls advise if otherwise):

PRIUS 2012 PHV (expected)
MPG (Hybrid) = 49 Combined City+Highway
MPGe (EV) = ?? Combined City+ Highway (not yet disclosed)
Utility Factor = ??% (not yet disclosed)
MPGe Combined Composite = 87 MPGe on sticker(Toyota estimate)

If we assume Prius EV MPGe is ~120 and utility factor is 50%, then we could get about 85 MPGe as the average of 49+120. Right?

 

...apparently the calculation method is more complex.
Try this: MPG = 1/((frac1/MPG1)+(frac2/MPG2)) ???
Sometimes you blend by reciprocals, not sure yet if this is such as case.
but even that is not total explanation, apparently they are doing it for city and highway too. There is a method number J??? they are using.

 

...wonder if Volt_2012 will have >60 too

 

This is a sample EPA label for a blended PHEV, like the plug-in prius.

See the white part of the driving range bar labeled gas + electricity with the little mark pointing up to the first box with a number? Take out the 65 and replace it with the 87 for the PHV, also shorten that white portion from 50 Miles to 15 miles. Then take out the 41 from the second box and replace it with the 49 for the PHV and you have a good rough idea of what your EPA sticker will look like.

I'd be willing to bet these are the numbers Toyota is thinking about as it releases info to the public. Anything to far off of this format would open them up to attacks of unreasonable expectations like GM got.

Also note my favorite part "All electric range = 0 miles".

 

I found this article describing everything about the fuel economy and labeling:

Federal Register | Revisions and Additions to Motor Vehicle Fuel Economy Label

 

The 15 miles described in the press release is "true EV operation and performance". It is not the blended range.

The blended range should be higher (could double) depending on how much gas got blended running through the test cycles.

 

Even if we use the 15 miles as the blended range and apply UF, we get this:

	Column 1
0	Prius PHV
1
2	City UF 0.31
3	Highway UF 0.31
4	Blended City 87
5	Blended Highway 87
6	City 49
7	Highway 49
8
9	Combined Composite 56.67

	Column 1
0	Volt
1
2	City UF 0.58
3	Highway UF 0.58
4	EV City 95
5	EV Highway 90
6	City 35
7	Highway 40
8
9	Combined Composite 56.87

If you round them up, the combined composite figure for both is 57 MPGe.

 

Blended mode is the term for a phev charge depleting range, if that vehicle can not run the tests without using gasoline. Blended PHEVs do not get pure electric range. It is this figure that toyota should be refering to when they state electric, or charge depleting range. The range and fuel economy are highly dependant on software. Double range does not make any sense at all with a 4.4kwh battery unless they are keeping the engine on all the time.

 

I don't think that will prove to be the case. If they tried to give a pure EV range they would need to put a huge asterisk next to it and give all the exceptions when they might still use gasoline, or explain why they have to have the EV-city mode which depletes the battery faster to stop the use of gasoline sooner.

I think you'll find that Toyota has invented a new kind of car; I 'd say a two mode hybrid except for the bad experiences GM had with the term.

You have mode 1 where it will operate as a hybrid with most of the power coming from the battery and small amounts of mechanical assist available on demand.

And you have mode 2 where it will operate as a conventional hybrid with most power coming from the fuel tank with limited electrical assist with regen power and what not.

The EPA is going to give you those two numbers, displayed on a sticker format like the one you found that I linked.

 

According to the actual procedure:

Determine the vehicle's Actual Charge-Depleting Range, R cda. Determine separate range values for FTP-based city and HFET-based highway driving, then calculate a combined value by arithmetically averaging the two values, weighted 0.55 and 0.45 respectively, and rounding to the nearest whole number.

For vehicles that use combined power from the battery and the engine before the battery is fully discharged, also use this procedure to establish an all electric range by determining the distance the vehicle drives before the engine starts, rounded to the nearest mile. ​

FTP does not exceed 60 mph and it is only 11 miles so it has to be repeated until the PHV battery runs out.



HFET also does not exceed 60 mph.



Based on that, I'd say Prius PHV has AER=15 miles.

 

We will see when the numbers are out. You were claiming it was much more efficient because it was blended, but gee now you say it no longer will do that. The demo phv couldn't accelerate for the test without turning on the engine. I am assuming this is the same. Could be wrong but 87 mpge sounds like they are still planning on using some gas.