OTOH..The Prius DOES recharge its batteries while driving - Bob Lutz

They provided the cost per mile and the price per gallon. We can get the MPG by doing a simple math. Where do you see any room for the misrepresentation?

 

On what planet? What color is they sky in your world? The math could not be clearer.

The only question I have is if they were trying to compare to some generic car rather than the Volt. That would be plausible.

Greenwashing my nice person!

 

Hey hey, let's not cross the line with person attack. John has been in hybrid tech before you and I. He may be seeing something that we are unaware of.

 

He made the personal attack(s) and crossed the line. He wants to accuse me of greenwashing while trying debate the meaning of "is". I'm personally offended by the accusations he has made. I'm particularly offended that he has intentionally misrepresented what I've been saying and trying to misrepresent me. I don't care who he is, when he started that BS he lost any respect from me.

 

There is obvious confusion about the information's purpose. This is what was asked:

Once the battery is depleted, what MPG will the system deliver?

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Sorry.

I simply had no idea a misunderstanding of purpose could be so extreme. No wonder GMI forum members got so worked up about this very same topic (which I did not participate in). Those that have followed hybrids & electrics for years refer to the industry standard of PER-MILE values, since no clarification is necessary. The $$$ automatically takes fuel considerations of all types into account. Converting to MPG is brand new... and most definitely not clear.

Please consider how misleading the measure of MPG is in the first place. It's shortcomings are the very reason most of the rest of the world use L/100KM instead.

Again, sorry.

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Tip of the iceberg. I've seen spin like this before... and some of it actually is unintentional. So, I may owe more of an apology.

Nonetheless, the information is still misleading and still being passed on. Cost per-mile includes other factors, not just gas. And of course, the values provided tend to be ideal-condition estimates.

By confronting someone unaware of what they are contributing to, you risk really upsetting them but also take the chance of creating a devoted supporter. Will he now go read the blogs posted by Volt enthusiasts? Seeing how different their perspective is can be very enlightening. I personally suggest study of the "314 MPG" claim, looking for the detail to support it in contrast to the comments made against both the GM & Toyota plug-in FULL hybrids.

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Hi Shawn,

This is not anything special. People - Engineers specifically - have been making series hybrid cars since about 1920. Serious research into them has gone on since the 1960's. Its nothing new or special to put a little hysteresis into such a system. And that hysteresis makes the possibilty of engine-only powering small. Like it is in the Prius. That is not to say if you try to do 70 mph up a mountain your not going to be down to engine-only power. It happens in a Prius. But, if you stay down below depletion speed - like 60 mph, then you top the mountain with battery to spare.

Another control alogrithm could work something like this. A running power average is kept in the computer, along with SOC. As the Volt climbs the mountain that running average will predict when the battery will reach min SOC. The computer is programmed to assume the past power average will continue on. Based on that the engine will be turned on before the min SOC is reached, and how soon its turned on is determined by how quickly the car is approaching min SOC. This makes the chance that min SOC minimul, since the car knows the rate of consumption, and the rate of replentishment (generator power output). Now, if you climb the mountain beyond the generator output power, then the battery runs down. If you stay under than generator output power by driving within the cars design - which should be about 60 mph for mountain climbing, then the battery will never run so low to require being protected.

 

What I was unaware of was that the factors in Per-Mile calculations were not obvious to everyone, especially maintenance. But I know now and certainly learned that lesson the hard way...

The costs included vary, but a couple of searches online revealed these in common:

• Fuel/Energy Expenses
• Maintenance & Tires
• Taxes & Registration
• Vehicle Price
• Finance Charges
• Insurance

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You know, that just won't fly at all. Why? Because GM used 2 cents per mile for the electric mode they compared to in the same sentence!

So let's make the assumption that you are making...for both electric and gas all of the above are the same except fuel. So let's assume that ALL of the 2 cents/mile is in the overhead and that electricity is free. :flypig: That means fuel cost = 12 - 2 = 10 cents/mile in gasoline mode and $3.60 per gallon. $3.6/gallon / 0.1 $/mile = 36 miles per gallon. Is this anywhere near 50 mpg? No. Is it reasonable to assume electricity is free? No. Does anyone believe the average driver would spend less than $300/year (assuming 15,000 miles per year @ 2 cents/mile) for "Maintenance & Tires, Taxes & Registration, Vehicle Price, Finance Charges, Insurance?" What you propose does nothing to explain the press release.

I'll point again to one reasonable interpretation of why 30 mpg calculated from the release would be in error: GM might have been trying to compare to some generic vehicle rather than their own Volt. The other claim you are making about the basis doesn't hold any water at all. Looks more like "spin" perhaps "unintentional."

 

GM issued a correction to it's correction:

Below a certain SOC the battery will gain charge from the ICE as power demands allow. Sounds like they are shooting for an 800 wH range, or 5% of total capacity.

MPG: I just don't see the utility in trying to arithmetize the conflicting GM PR statements. Seems reasonable to me to expect the ICE to have an efficiency of 36 - 40% in non-aggressive driving, and transmission losses to the wheels of 10 - 15%. The end wheel motive energy is therefore is going to be (based on 36 kwH energy per gallon of fuel) in the range of 11 - 13 kWh/gallon. Anything more specific will have to wait for production cars. Anybody counting should realize this range is where the Prius sits, too, for most people.

If I may be so bold, I'd say hypermilers will post better results than the Volt by ~10%, while median drivers will reverse the results. The serial and parallel designs each have tradeoffs, and at least on paper I don't think one is clearly superior even in most driving scenarios. That said, I trust Toyota to implement and compete on price better than GM any day of the week.

 

I wonder if the Volt will have 'glide' capability or if it is only a two mode 'choice' of electric drive or re-gen coast. I gain a lot of 'free' miles per tank by gliding the slight down hills on which I can maintain speed and gliding to signals/stop signs.

 

The Volt's design benefit is gliding. The trade-off is system inefficiency when ICE is in use.

 

I would have to agree. Classically the $/mile cost of a car was used to indicate mainly the total operating cost. But it has become common as of late to define fuel only costs this way, with the rising cost of fuel being on everyone's minds. This has been particularly true when discussing mixed fuel vehicles like PHEVs, flex fuel, etc. 2c/mile sounds right on to me for the fuel only cost of all electric operation. From that it would makes sense that the gasoline only cost would be fuel only as well.

For another sanity check, according to Edmunds over 5 years a Prius costs 61c/mile to operate. Consumer Reports says 45c/mile for 5 years, 40c/mile over 8 years. I don't think its reasonable to assume that the Volt running in ICE only mode will cost 4-5 times less to operate than the Prius.

I'd say the assumption that the 12c per mile is fuel only is very reasonable, and the 30mpg calculation is yet another conflicting piece of data that should be considered.

Rob