Unfair Competition for the Chevy Volt?

Wow, That is remarkable. You would think just a shred of common sense would prevail on this matter... unfortunately It seems less and less people seem to have any.

It's amazing to think that something with as much media attention would be so dramatically flawed... Well I guess it happens every day in politics... wait a minute! I think we have a marriage of politics and well, something else... I was going to say engineering, but I don't think Engineering or physics has any hand at play.

Flaws everywhere, but you act as if you were surprised by that! Once again we are dealing with salesmen running the thing and not engineers!

Don't you understand "Smoke and Mirrors"??????????

Blink, You made me curious; what kind of electric motor and energy supply are you using for your project?

This looks like a simple case of forgetting to divide the addition of the two values to get the average.

To me the whole concept is flawed in that it depends where the electricity comes from in the first place. If the source is hydro, solar, aeolic it cannot count the same as, say a coal fired power source.

I'd love to run an EV but it would make no sense as about half of my energy comes from my diesel generator.

Regards, Chas

To me the whole concept is flawed in that it depends where the electricity comes from in the first place. If the source is hydro, solar, aeolic it cannot count the same as, say a coal fired power source.

I agree. I think the best approach to rating electric cars and PHEVs (in the US) is to use miles per kilowatt-hour for electric consumption and miles per gallon for liquid fuel consumption (...or in other countries, the equivalents, with both units and nominator-denominator relationships chaged to fit convention.) The latter has been used here for many decades, and people understand it easily. Most electric vehicle owners understand miles (or km) per kilowatt hour. The two separate figures give you information that is obcsured it they are combined into one figure. Only with the two figures can you make informed decisions regarding the cost and environmental impact of of using a fuel or electricity.

It would seem that you should measure the amount of energy consumed to cover the distance that can be duplicated by the general public. A purely gasoline or E85 or diesel powered vehicle would be easy because it is purely chemical.

The EV and PHEV gets interesting since the external electricity has to come from somewhere. You could claim that all your electricity comes from a windmill and has no chemical energy cost but that would be like saying the vehicle gets an infinite mpg on foreign oil because it only uses domestic oil.

One solution would be to use the amount of chemical energy used to create the average unit (watt, kilowatt,...) of electricity in the USA.

Remember also that it is not the amount of electrical energy expended to move the vehicle but the amount that is put in from the 'wall socket'. If the efficiency of your charging system and the batteries is poor then you would be using more electricity from the external source.

Once you have the total chemical energy used to cover a mile, you would divid by the chemical energy in a gallon of gasoline.

One solution would be to use the amount of chemical energy used to create the average unit (watt, kilowatt,...) of electricity in the USA.

I think this is a good approach (and in fact the best approach from an environmental standpoint). (This approach is often referred to as well-to-wheels, even if the well-to-pump or well-to-plug losses are not completely and accurately accounted for.) The difficult work of determining the losses involved in generating electricity on average across the US has been done. The GREET spreadsheets from Argonne National Lab show the relative resource consumption to produce electricity, ethanol, biodiesel, gasoline, etc.

People from California argue that they are more efficient that the rest of the country -- in fact they argue so strenuously that they have their own place in the GREET spreadsheets. But the differences are small in comparison to the huge differences that come from different methods of computing vehicle efficiency. (Chevy says 230 mpg for the Volt, whereas on a well-to-wheels basis, using the GREET numbers from across the country, the figure would be more like 50 MPGe.)

The well-to-wheels figures have the advantage that they are closer to the figures we are accustomed to, and "make sense." So when (about a decade ago) the DC EV club published 59 MPGe (well-to-wheels) for the GM EV1, that number made sense: You can understand that the number should be high (as compared to a small sports car of the day) because the car was designed and well-optimized for high efficiency. But the number should not be astronomically high -- because about 62% of the fuel used to generate electricity goes off as waste heat -- and that figure is in the same ball park as the number for a car engine. (The Prius engine peaks at 38% -- an outstanding number -- and runs at close to that figure much of the time, by virtue of the hybrid system. Coincidentally, the average grid efficiency is also 38%.)

The GM EV1 (before they were crushed) consumed 190 watt-hours per mile, which produces a figure of 179 MPGe per the Progressive Insurance Automotive X Prize calculator: about three times the figure the DC EV group came up with. While some people may swallow this figure as being realistic, I don't think many engineering types will. It suggests that the EV1 was 6 times as efficient as its contemporaries, which of course, it was not.

For PHEV's, the issues are further clouded, because a PHEV can operate on either one energy source or another, and if the consumption figures are different for the two sources, then the distances operated on each source must be specified. This can get very convoluted, and even with a particular test trip distance specified, some info critical to the consumer would get left out if only an MPGe number is given. If the test trip length is, for instance, 100 miles, then the result is not meaningful to someone who uses the car mainly to commute 30 miles round trip (which on a PHEV40 would mean that the gasoline engine never fires up).

Using two simple figures, miles-per kWh (for when operating in charge-depleting mode) and mile per gallon (for when operating on gasoline -- i.e charge sustaining mode) avoids the issues re 1. what "equivalent" means, 2. whether well-to-wheels or pump to wheels should be used, 3. artificial trip lengths, etc. PHEVs operate in two distinct modes, and a single figure cannot provide sufficient info to make an informed buying decision. At very least, the buyer deserves to get figures that show 1. How much will my electric bill increase, and 2. how much will my gasoline bill be reduced. (Neither of these can be specified in dollar amounts, because the prices vary, so specifying in kilowatts and gallons allows the buyer to do the simple math.)

Two simple, understandable figures are much better than one complicated and misleading one. This is especially so when the complicated one (MPGe) comes in so many different flavors.

Remember also that it is not the amount of electrical energy expended to move the vehicle but the amount that is put in from the 'wall socket'. If the efficiency of your charging system and the batteries is poor then you would be using more electricity from the external source.

Again, you are correct, and again this is an area in which the Progressive Insurance Automotive X Prize spreadsheet is completely incorrect. Time connected to a 15 amp circuit has little to with the energy consumed to charge a vehicle. The charger 1. does not typically draw full circuit rating amperage even at the start of charge, and 2. always draws less as the charge proceeds, according to the charge algorithm, the battery's charge acceptance rate etc. My own vehicle draws power from a 15 amp circuit, but even at the start of charge the charger draws only 4 amps from that circuit (with battery current roughly doubled and voltage roughly halved from the plug values). At the end of charge, it is drawing milliamps.

Hi K..Blink. Having not payed much attention to what is going on with the X-prize although always intrigued, I'm extremely disappointed in this issue. Bias has definitely, in my opinion, taken over. For those paying attention, rather blatantly. What ever happen to keeping it simple? I would like to see that competition played on solid ground with some logic applied to it's structuring of the rules. Just my quick response to an event that has much merit but as usual has it's seemingly unfair idiosyncrasies. Best of luck to you in the competition anyway. Your concept idea has always been sound in my opinion.

There is an article on how MPGe is calculated in the latest issue of Road & Track. It states that a pure electric car, i.e one that doesn't even use a combustable to heat it, gets a multiplication factor of 6.66667. IIRC this means that the real MPGe is multiplied by 6.66667.

As Click and Clack would say "Boooogus".

Yes, you are right, that is exactly how it is done for for CAFE purposes. And your take is also right... it's bogus.

This figure (written as "divide by .015" in the law, which means multiplying by 6.67) was first called "scarcity factor" and now has a different name, but it applies to any alternative fuel (which is completely idiotic -- it could apply to ground up spotted owls, or ground up sequoias, for example). Where this calculation shows up in practice most often is with flex fuel vehicles. If you have a flex fuel 15 mpg SUV, it is assumed to run half the time on E85 (already a bad assumption -- maybe 2% is realistic... maybe lower yet?). Therefore, the multiplier for a flex fuel vehicle is half of the 6.67, 3.33. So suddenly, this gas guzzler is rated at 45 mpg, about the same as a Prius. (You can see why GM makes flex fuel SUVs, and promotes them as being green".)

Interestingly enough, the same law starts off making sense, and uses a well-to-wheels method to come up with the MPGe that gets multiplied non-sensically. The well-to-wheels method acknowledges that electricity is not free, environmentally or in terms of resource depletion, and in the CAFE law, the figure used for generation efficiency is (IIRC) 32.8%, and distribution efficiency is also accounted for, at something like 90%. It is ironic that the basic number for an electric car (before it is inflated) has some good science behind it (and that science, i.e. getting to the point of being able to say what the overall grid efficiency is nationwide, required many millions of dollars of research). Then, they take a good figure and apply politics, the only arena in which it can possibly make any sense at all to consider one alternative fuel just like another.

Pimental's study re the amount of energy it takes to make ethanol found that the amount of petroleum invested alone was greater than the net energy value output of the ethanol from corn. So, if you believed his study, you would conclude that the multiplier should not be 6.66, but perhaps .9 or .8 etc. His study is not rock solid, but a researcher from MIT, (IIRC) did a survey of many such studies and found that (averaging the studies) ethanol is produced at a slight net gain, but only slight... nothing remotely close to 6.666... (Of course, averaging results of studies is not particularly valid scientifically... but it does provide a general feel for things.)

Most of the flavors of MPGe are sold as a means for Joe consumer to evaluate one energy source vs another. Most do the opposite, by clouding the issues, some very dramatically and deliberately so. The Progressive Insurance Automotive X Prize standard (which is different than the well-to-wheels standard that has been used for ages) is an example of one such method that makes electric cars look far more efficient than they are. In this method, electricity is considered a fuel (despite the fact that it has none of the characteristics of a fuel, such as easily measured mass and volume, the ability to burn, and the critical one -- that using a fuel means depleting a resource, whereas electricity is not depletable). The effect of MPGe for an electric car is that it completely obscures the fact that for the average consumer, using electricity means burning something remotely.

On a well-to-wheels basis, the old GM EV1 got 59 MPGe -- a very impressive figure. The cost of operation was even more impressive, because electricity is cheap, as compared to gasoline, most of the time. The Tesla Roadster has been advertised at 135 MPG, but in fact is much less efficient than the GM EV1 was. Its actual energy consumption is 310 watt-hours per mile, whereas the GM EV1 was 190 watt-hours per mile. As an electric car, the Tesla is an electron guzzler, a fact which is thoroughly disguised by the 135 mpg rating. Naive buyers of the Tesla think they are doing something great for the environment, but the fact is that a Tesla powered from the national grid mix generates more CO2 than a Prius. The Tesla claim of 135 MPG and the Progressive Insurance Automotive X Prize (sorry for the wordy title -- my contract with them requires this) MPGe of 109.8. To a naive consumer, that figure makes the Tesla seem more than twice as "good" environmentally as the Prius. That's a significant distortion, as anyone who runs a power plant can tell you.

Scan down to a post from Feb 7, 2008 by Ken Fry to see the formula used in the CAFE standard (the rational part, not the political 6.67 part).

The new Nissan Leaf was rated by Nissan at 367 MPGe. It, too, is no more efficient than the GM EV1 (which was rated at 59 MPGe by advocates for EVs, not detractors... in fact I am an advocate for EVs... after all, my prototype runs most of the time on electricity). (If you take 59 MPGe and multiply it by 6.67 you get 393.53) The real figure for the Nissan, before applying politics is 376 / 6.67 = 55.02 MPGe.

I strongly favor watt-hours per mile (or the equivalent, miles per kilowatt-hour) for electric cars and for the charge depleting part of a PHEV cycle) because this is very hard to game, and would show that the Nissan Leaf an GM EV1 are efficient people carriers, and that the Tesla is not. (Actual electrical efficiency is almost a non-issue: my own prototype is at the low end of electrical efficiency for vehicles that are a little ahead of 30-year-old fork lift trucks at about 88% between motor and controller. The Tesla is about 91%, and the Leaf might be slightly better [maybe 92%]. [At very low speeds, my actually electrically more efficient than the others, because the motor is more heavily loaded, and at very light loads electric motors are not efficient.] These small differences are completely meaningless in comparison to the big differences, which occur elsewhere in the vehicle: weight, aero, frontal area, rolling resistance, etc. Those big differences make my car 3 times as efficient as the Tesla, and would apply if the two vehicles were both powered by diesel engines or gas engines.

For liquid fuels, ordinary MPG is far better than MPGe, because we buy fuel in real gallons, not equivalent gallons. (and because there is no agreement on what "equivalent" means: cost, energy content, environmental impact, etc. etc.)

I've seen Flex Fuel vehicles here in Connecticut, but the only E85 stations I've been able to find are private, so there is no place to buy the stuff.

That rule for figuring MPG for a Flex Fuel vehicle makes the idea of the proposed/future CAFE standard of 35 MPG a joke. All the manufacturers have to do is make each car Flex Fuel and they all meet the requirement.

Isn't government logic wonderful.

Government logic? This is the first I've heard of this. What is this Unknown thing?

Now, Correct me if I'm wrong... But, Isn't energy just energy? Isn't it all just measuring energy? How can they get away with saying anything else? Measure the Damm energy, put all the energy into the same units, and compare... how can it be that difficult. We know how much energy is in a gallon of petrol, we know how much energy is moving through a wire, we know how much energy is bombarding a given solar panel at a given time... we know how to convert each of these different energies into the same comparable unit... why are those people over-complicating and fudging the results in someone's favor, instead of letting science determine who is the most Energy efficient. Wait... I forgot about politics, and abuse of power... I love how someone can be persuaded that the laws of science don't exist, so they can make an extra buck. Makes me want to puke.

RVZ717 -- You're right. Energy is energy. It's all kilowatt hours (probably the best unit to use if we are doing comparisons of various sources and technologies). But energy measures are of lesser value unless we do our comparisons at the point of useful energy delivery. In our common motor vehicle applications that is where the wheel pushes against the ground. Comparing the energy content of gasoline with the energy content of electricity before they are loaded into the vehicle ignores the important differences in efficiency of the energy conversion process that goes on within the vehicle between the fuel storage and the wheel contact.

But really the best comparison would be based on the costs of the energy delivered at the wheel or whatever is the actual point of use for other energy applications. These costs are the following (and maybe some others):

1. Costs to deliver the energy from its source and convert it to usable form.

2. Cost of the entire transportation system (vehicle, infrastructure for operation, production, maintenance and disposal)

3. Environmental costs of delivery, conversion and actual use plus 2. above

4. Costs arttibutable to depletion of the energy resource.

5. Other social costs attributable to the above.

(quite a cost accounting challenge here)

Ed Weldon

Well, strictly speaking for the competition, none of the environmental, or social cost's are a factor. Only how far can you make the contraption go on a given value of energy (whatever form it is in). For the competition, I would think that measuring the energy which is put into the vehicle would be the best way to compare energy efficiency of the contraption itself. measure input energy, track the distance traveled with that given value of input energy, and then you can figure the actual efficiency of the conversion from input energy to output distance. I dunno... maybe that's too easy, of flawed somehow... seems rational to me.

I would think that measuring the energy which is put into the vehicle would be the best way to compare energy efficiency of the contraption itself.

That's the sticking point. If you measure the BTU value of a fuel and compare that to the BTU value of electricity, the comparison is immediately not apples to apples. Electricity is not a fuel and is not depleted, and doesn't have the characteristics of a fuel, such as easily measured volume and mass. It can only carry energy from one point to another. So when you compare an energy carrier to a fuel you have to start at some point where the two can be compared apples to apples -- and that is at the fuel: coal (plus etc.) vs gasoline.

Otherwise, it is obvious that any electric vehicle wins on a plug-to-wheels vs pump-to-wheels comparison. Electric motors are 90% efficient, and gasoline engines are 25% efficient -- there is no point in having any liquid-fueled (or partially liquid-fueled) vehicles enter. But that contest would not be an indication of actual resource usage, and resource usage is the key theme of the competition. The competition was conceived as a means to promote one of the things society needs -- that is the case for every X Prize. We don't need efficient cars to simply talk about them. We need efficient cars to reduce resource consumption and CO2 generation.

If that is the goal, then you have to go back to the fuel -- the thing that we are trying to save. That is where the competition says one thing but does another, because a vehicle that guzzles electricity gets a better rating than one that sips gasoline, or ethanol or biodiesel. There is no accounting for the coal. The rules make the competition not about reducing resource depletion but only about promoting electricity usage.

I understand what you are saying, However, It still boils down to how much Energy is consumed moving from one place to another. What If my electric car is given electricity from a windmill, or waterwheel on my own property, and no "Fuel" is consumed in the process, (extraction of energy from the atmosphere). Can't you simply convert the BTU value of fuel to a unit which can be compared strictly as energy, such as Jules? I understand that electric motors are FAR more efficient than a gasoline motor at converting energy to work, isn't that the point? I mean, in my mind, the whole point is to create a vehicle which converts energy to work in a very efficient manner.

I understand electricity is not fuel, I understand fuel is not electricity... and I also understand that they can both be looked at as energy. It just seems like it being way overcomplicated and politicised.

I also completely understand about the upstream consumption... but... lumping all energy sources into one general group to get some "conversion value" seems really inadequate to me. Not all electricity is made from burning fuel, In fact here in Oregon, the vast majority of our energy comes from hydropower (where the only resource burnt, would be the poor fishies who don't have a breeding ground anymore)(they are trying to get a bunch of energy producing dam's torn out, to replace them with wind power). We are dismanteling one of the few coal powered plants in the area soon as well. So how do you compare BTU's to hydropower? Would you not have to bring them to the same unit as well?

I agree with both you and RVZ717. The X Prize folks want to promote their particular MPGe scheme to beyond the competition, to make it the standard for the country, which I am opposed to because it disguises the actual energy source consumption, and produces figures that are all out of whack with what the public understands as the environmental "goodness" of one car over another. The X Prize people would, if the instructions for their spreadsheet are followed, give the Volt a rating of 30.9 MPGe. If the competition guidelines are followed, the figure is over 100 MPGe. So first, they must at least get their own act together before promoting the scheme for use outside the competition.

I think your list of things to consider is correct, and we have (as a country) a lot of the required data already. We also have huge disagreements (as individuals and groups within the country) re the social value of green energy vs profits, supporting existing industries like the oil industry, etc, etc, etc. However, little of this needs to be part of a fuel efficiency rating, Instead, it should be part of "an informed populace" the cornerstone of democracy... here, we've failed miserably. If all these issues are worked into the rating, you are right, there will be no consensus.

As engineers, though, I think we can all agree that if a car uses two different energy sources, we need to know how much of each is used to make an informed buying decision: miles per kilowatt-hour; miles per gallon.

The X Prize MPGe (which I will call XMPGe to distinguish it from all the other flavors that have existed and are proposed) figure for plug-in hybrids requires the input data you or any engineer would think necessary: the amount of electrical consumption, the amount of fuel consumption, and the distance traveled on each. (A part of the contentious nature of it: what is the appropriate distance? Standard MPG does not change with distance traveled. XMPGe does.) (For the most part, miles per kilowatt-hour also does not change with distance -- in other words in the first 40 miles per day of Volt operation, this figure remains around 4 miles per kilowatt-hour.)

After you have this basic data (from EPA tests) then XMPGe cooks the books by combining those into one figure which hides the original data. (If the answer to a math problem is 4, what were the original numbers added or multiplied together? Who knows?) By hiding the original data, the Volt would gets a very high XMPGe figure, (per the rules, not the spreadsheet). That would make it appear environmentally "better" than the Prius, by a factor of about 3. That is a significant misrepresentation if we are concerned for the environment, and I would argue that any replacement for MPG (which does correlate with environmental "goodness") should also reflect environmental "goodness". The only way to do that, if such a scheme were implemented would be to use nationwide averages for well-to-pump losses, which we have from the DOE, etc. But this all gets much too complicated, much too quickly.

The consumer should know the miles-per-kilowatt-hour of electricity consumed and the miles-per-gallon of gasoline consumed. MPGe obscures these critical facts. With these fact in hand, then anyone who is not functionally innumerate can easily calculate the costs of each and can (with reasonable education) assess the environmental impact -- the buyer can then be an informed consumer. The education part of it will always be hit-or-miss, but that is an issue separate from simply supplying the info consumers need, which MPGe fails to do.

As a driver of a plug-in hybrid, I can say that not once have I wanted to represent its efficiency is a single number. Given that the vehicle is routinely supplied two very different sources, one fuel and one an energy carrier, it is easy and meaningful to keep the calculations separate. (I much prefer to run on as much electrical energy as possible, not for any environmental reason, but simple because the car is quieter and more comfortable that way.) No PHEV driver can escape the fact that his vehicle runs on two different energy sources (one of which can represent fuel burned, water fallen, sun shone, etc.) (Fail to charge it, and it becomes immediately apparent that the car runs differently.) The vast majority of consumers will want to know: how much will this cost me (in dollar terms, and perhaps in environmental and national security terms) and the only way she can know that is by looking a how she uses the vehicle, not by looking at how someone else might use the vehicle. MPGe can only tell you how someone else might use the vehicle, and obscures the data you need to make simple calculations.

There is a certain arrogance to the Silicon Valley approach. It is almost as if they think they are the discoverers of electric vehicles -- but Porsche was building electric vehicles and plug-in hybrids in 1904. They talk about how obsolete the MPG figure is, but for 99% of the buying public, this figure will remain central for many years to come. For the rest the MPGe figure simply hides data needed to make an informed decision.

MPGe is OK for a competition (although I personally think it is the wrong metric there too) but it is certainly not the right metric for general use. Imagine the difficulty in knowing what the effect on your electric bill will be, if all you have is an MPGe figure.

In this post on the Progressive Insurance Automotive X Prize site, I argue that XMPGe is both unnecessary and undesirable.

I agree with much of what you are saying here. I don't favor any of the MPGe flavors for posting on a car window, because they make what could be simple, complicated. If a car goes 4 miles per kilowatt-hour a buyer can easily figure out the economic cost, and if they are concerned, they can also figure out as many of the other costs as they see fit. Almost anywhere in the country, with todays gas prices, it is much cheaper to drive and electric car, if you ignore battery replacement costs... which of course you cannot do... so again things get complicated.

As you say, if you have solar or wind power, an electric car is light years ahead of an ICE car, but you will still probably want to use your wind power wisely, because there are costs associated with wind power. Having the miles-per-kilowatt hour figure allows you to compare one vehicle with another, and also relates to battery replacement cost: cars that consume a lot of kilowatt-hours use bigger batteries, or put more cycles on same-sized batteries.

If an MPGe figure is given, then you don't have the info you need to figure out operating cost directly, even if the vehicle is all electric. You first have to know the BTU value of gasoline, and the btu value of a kilowatt, and then work backwards to a figure that the manufacture already knew from doing the testing. For a plug-in hybrid, you also don't know the relative distances on gasoline and electricity, so you don't know how many of the miles (per gallon equivalent) were on electricity and how many were on gas.

If instead of MPGe, you have the range on electricity, the miles per kilowatt, and the MPG, you have all the information you need without introducing any new concepts or complications.

It just seems like it being way overcomplicated and politicised.

I think the whole issue of car efficiency can be overcomplicated or oversimplified, and is always politicized, because there is big money in having your car (as a manufacturer) look better than the next guy's. GM has been very good in playing the flex fuel game to avoid CAFE fines, and you can be sure that their lobbyists helped put the 3.33:1 advantage (for flex fuel) and 6.67:1 advantage for electric vehicles into the law. If Joe congressman says that electric vehicles should be promoted because they are "cleaner" then Jim congressman from and oil-producing state says "just a gull dern minute, coal creates more CO2 than gasoline, and this law has to apply equally across the country so we have to use the grid average, not the figures from a particular state or locality with a bunch of windmills." This sort of back and forth leads to the complex laws we have regarding this stuff.

So how do you compare BTU's to hydropower? Would you not have to bring them to the same unit as well?

Yes. Actually all these units are just different names for the same thing, so BTUs, Kilowatt-hours, Joules, Horsepower-hours, etc, all easily convert. But that is only the first step in comparing, for example, coal burning with hydropower or nuclear. Nobody wants to flood old towns and homes, or have a nuclear plant or coal burner in the back yard, so this gets political quickly.

This other thread talks about some of these issues, if you are not already worn out.

Your points are well-taken, and I would prefer a system that measures the energy required to move the car through an existing test sequence. People engineering vehicles, like me, already have this data -- I can tell you what the energy consumption rate is for my vehicle at any instant on the EPA urban cycle, for example. It takes very little energy to move a small, light, streamlined vehicle around.

Unfortunately, there is the issue of how you feed the car: do you use a fuel, or do you use an energy carrier, like electricity, where the fuel is burned remotely? If you have a small generator in your backyard to supply your electrical needs, you are painfully aware that the resource consumed is diesel fuel. Stick that generator in the back of a car, and throw in a couple batteries, and you have a plug-in hybrid. Then replace the backyard generator with another one just like it.

Do you power the vehicle with the onboard generator or the one sitting in your back yard. It costs the same either way, and the actual resource consumed in both cases is diesel fuel, in essentially the same quantities. (We are ignoring some weight issues in the vehicle, but these turn out to be very very small -- my vehicle can operate as a pure electric of reasonable but not great range of about 80 miles while weighting the same as it does as a PHEV 40.)

The Progresive Insurance Automotive X Prize people have long claimed that electricity is a fuel. Obviously it is not. (You will not find it defined as a fuel in any chemistry text or physics text, or even a plain english dictionary.) The advatage of doing this, if you are trying to sell electric vehicles, is that you then ignore the fact that resources are depleted (and polution generated) to make electricity. You can claim what seem like incredibly high "effieicncies" if you then create a MPGe, knowing that people justifiable think of a 50 mpg car being more "efficienct" than a 20 mpg car.

TheTesla roadster, an electron guzzler, is rated 109.8 MPGe (per the competition metiric) and the is Prius a 50 MPGe vehicle (per the same metirc). To the naive, this makes the Tesla seem very efficienct. But it is no more efficienct that the Pruis at actually moving people down the road, even if you only put two people in the Prius. The Prius consumes 250 watt-hours per mile, and the Tesla consumes 310... but the competition metric makes the Tesla look better, not worse. So much better, that it is hard to avoid the conclusion that Elon Musk, the Tesla guy, has undue influence over the competition, by virtue of being on the Board of Trustees fot eh X Prize Foundation.

The Progressive Insurance X Prize people would say that they are in tune with your take on the issue: They take the energy value of electricity and express it as its BTU equivalent in gallons of gas. Doing so obscures that fact that the "equivalence' is not a true "equivalence:" electricy is not a fuel, and fuel is not electricity. Electricity can be produced in many ways (a compelling advantage for electric vehicles) but the most common way, by far, is by burning a fuel. A fuel is not "energy" it is an energy source, that when processed by burning, yields heat energy, which can be mechanically converted into electrical energy, with substantial losses along the way.

I much prefer the simple miles-per-kilowatt on electricity metric (which eliminates the incredible differences in rating of the 59 MPGe (WTW) of the GM EV1, the 109.8 MPGe (PTW) of the Tesla, and the 367 MPGe of the Nissan Leaf. (WTW times 6.66). All these are roughly equal when measured WTW, with the GM being the most efficienct, and the Tesla being the least. The Leaf calulation is the only one that actually is in accord with existing law, strangely enough. (The watt-hour per mile figures: Tesla 310, Nissan 200, GM 190 -- simple, eh?)

For liquid-fueled cars, MPGe just adds confusion, and makes a simple question "how much is this going to cost me to run?" much harder to calulate.

Second best is to use the well-to-wheels approach, because it takes the necessary step of converting the fuel into energy into account -- and also happens to result in figures that "seem" about right. The GM EV1 was more efficienct in turning coal into motive power than contemporary sports car were in converting gasoline into motive power. It also has the advantage that it is already written into law (but unfortunately then politically perverted by the 6.67:1 multiplier used in the CAFE calulations.) WTW has often been used (without political multipliers) in vehicle competitions where environmental impact and resource depletion are issues.

The other MPGe's are worse, because they are based on non-science (such as the contention the electricity is a fuel) or are useful only for cost comparisons alone, which in this day and age, are generally considered short-sighted. (We have plenty of old tech solutions, involving asbestos, lead, mercury, etc that were cost-effective.) Coal, (ditch the emission controls) is definitely the way to go in terms of cost alone.

This is what the law says, in the rational part:

"When comparing gasoline vehicles with electric vehicles, it is essential to consider the efficiency of the respective "upstream'' processes in the two fuel cycles. A full description of the differences in the processes is beyond the scope of this rulemaking, but the critical difference is that a gasoline vehicle burns its fuel on-board the vehicle, and an electric vehicle burns its fuel (the majority of electricity in the U.S. is generated at fossil fuel burning powerplants) off-board the vehicle. In both cases, the burning of fuels to produce work is the least efficient step of the respective energy cycles."

Then later in the whacko part:

"The 1/0.15 factor used in the equation is not intended to be a scarcity factor per se, but it does result in a very substantial adjustment to the raw calculated energy efficiency of electric vehicles. It is included to reward electric vehicles' benefits to the Nation relative to petroleum-fueled vehicles, in a manner consistent with the regulatory treatment of other types of alternative fueled vehicles and the authorizing legislation."

Tha actual law is here.

Yes this is one of those things that we can talk about forever. Your talk about a conversion to say that there could be some "energy per mile" number to compare different types of power already exists......"dollars per mile". I check mileage with all my cars and put down, along with number of gallons used, how many dollars the tank of gas costs. i think that is what people really are concerned about. It seems that we would rather hear some number that does not remind us how much MONEY we are spending to get down the road.

I find that many times that big mileage (dollars per mile) increases come from just finding the cheapest gas in town and buying it there.

The big test with electric cars will be separating what it costs to run your house from what it costs to charge these batteries.

I guess that what will be the best test of the electric car, or what ever is the latest "green, efficient, carbon footprint, blah blah blah vehicle" is will be what ever is easiest on the consumers wallet.

beware of the missed placed decimal point..........