87 MPG(e): Toyota Confuddles PC experts

I think there is a 4th key point. Recharge time of 1.5 hours for PHV and 4 hours for Volt. That shows not only the time but also the amount of electricity required to achieve 87 MPGe vs 93 MPGe.

PHV 1.5 hours -> 87 MPGe
Volt 4 hours -> 93 MPGe

PHV 0 hour -> 49 MPG
Volt 0 hour -> 37 MPG (premium gas)

 

Good point. We also need the blended range of Prius PHV and the All Electric Range of the Volt.

 

Toyota has given you the blended range of the PHV, its on their website at 15 miles; I am confident they know that is what the sticker will say.

You know the all electric range of the Volt, it is 35 miles on the EPA, most people get more in practice.

What we really need to know is how much gasoline does the PHV add to the charge it got from the wall to travel the same distance as the Volt. If we charge them both for 1 hr on a 110v, the Volt will go about 4 miles. If we divide the blended range of the PHV by the charge time we get that it should go 4.2 or so miles before switching to HV, but what we don't know is how much gas the PHV burned going those 4.2 miles as well, or conversely if we figured out how much energy was in that amount of gas and allowed the Volt that much additional energy as well, which one would really go further (probably the Volt since it is rated about 7% more efficient during CD operation).

 

I'm sorry I'm not communicating more clearly. Let me try an example with your numbers:

Volt = 360 Wh/mile = 5.4 kwh used in 15 miles
PHV = 300 WH/mile = 4.5 kwh used in 15 miles (ignore for now the battery is not that big)

If that was that I think we'd agree the PHV would travel further on one hour of charge because its using the Wh's given it to greater effect.

However, what I am saying is what if the PHV also consumes 0.05 gal of gasoline during that 15 mile trip (rate of 300 mpg while in CD mode). A twentieth of a gallon is over 1.5 kwh of energy so the PHV really used more than 6 kwh of power, despite the fact it only charged 4.5 kwh.

Looking at only the electric numbers on the PHV when both are consumed together is misleading.

 

My best guess is that MPGe will be on par or higher than the 99 MPGe for the Leaf, and at the very least higher than the 93 MPGe for the Volt.

 

Toyota has already preliminarily estimated it at 87mpge. Why do you think they are so far off?

 

We don't need to guess the number Toyota gave us its 87 mpge.

If you go back and look at the sample sticker, the two numbers we don't know yet that will settle this for the most part are the gallons per 100 miles consumed in CD mode and the kwh per 100 miles consumed in CD mode.

With those two data points we know everything that will be on the sticker, and you can compare the electrical consumption at that point with actual EVs if you like but you'll need to factor in the gasoline consumption as well.

My prediction is electrical consumption will be around 20 kwh per 100 miles and gas at around 0.7 gallons per 100 miles.

 

Problem is your all electric only non-blended range will equal zero miles.

 

Based on comment #2 I was making a guess as to what the EPA may designate as they have done for Leaf/Volt.

I guess I was interpolating/extrapolating a number based on EV driving only (if that exists on a PHV).

In my mind, to compare Leaf's 99 MPGe and Volt's 93 MPGe, you have to compare Prius PHV while consuming battery power only or the numbers are apples/oranges. I could be wrong though.

The EPA may give a different designation since the Prius is not a pure EV across all conditions.

 

I'm thinking a reasonable usable range on the battery is going to be about 3kwh, so divided over the 15 mile range gets the 200 wh/mile.

There was an article on here that reviewed one of the mules that got fuel economy results that indicated to me the CD gasoline mileage was around 125 mpg. I figure the production model is probably a little better than that and measured under more ideal conditions, so I think around 150 mpg is reasonable, so somewhere in the neighborhood of 0.7 gallons per 100 miles (being a little generous).

I don't really know if those two figures mesh together in any particular way to work out to 87 mpge, but using the numbers on the sample sticker as a comparison my estimate is that its about right.

 

Leaf and Volt are directly comparable because the ratings were arrived at the same way. The PHV is going to use gas during those same tests so won't rate the same way.

I suppose the best way to test would be to drain every last drop of liquid fuel from both a PHV and a Volt, charge them both for the same amount of time, and then drive them along the same track at the same speed, to see which goes further and how much. That way the ICE's couldn't help out even if they wanted to.