230 MPG?

Update:  230 MPG turns out to be, as I suspected, total BS.  Make sure to check out update at bottom

Apparently under new methodology, the Chevy Volt got an MPG rating of 230.

we're told that the Volt has snagged a staggering 230 MPG rating in the city, but we should caution you that it's not as cut and dry as GM would have you believe. The EPA has released "a new methodology for determining a draft fuel economy standard for extended-range EVs like the Volt," and it's that murky measurement system that has blessed Chevy's wonder child with a triple digit MPG rating.


Forget for the fact that the whole terminology is meaningless, as the vehicle only burns liquid fuel for a portion of its energy needs, so "miles per gallon" is an odd concept.  But one could imagine that one could look at the miles per electrical charge, and then look at the equivalent gallons of gasoline-equivalent BTU's it took to deliver that electricity, and create an equivalent MPG.  In fact, that's the only approach that makes any sense to me.

If so, these numbers imply that it is 10x more efficient to burn hydrocarbons in a large utility plant boiler or gas turbine, convert the combustion energy to electricity, transmit that electricity hundreds of miles, charge up a set of car batteries, and then drive an electric traction motor from the batteries than it is to burn hydrocarbons directly in an internal combustion engine in the vehicle.

If this is really the case, then I have been selling electric cars short and we will all soon be buying them (I prefer the performance of an electric engine so this kind of fuel savings is just icing on the cake).  However, I have my doubts.  While certainly a large power station is much more efficient in using all the BTU's in a fuel than is an internal combustion engine, when one considers losses in the electrical generation and line losses, I find it very very hard to believe the difference is 10x.

But I am sure there is no conflict of interest here, and that it is pure coincidence that GM is owned by the same people who created the new methodology and did the testing, and given that the new methodology was created by the same people who have been pushing electric cars as a policy alternative.

Update: The 230 MPG figure is even more BS than I thought.  Apparently, MPG while running on batteries is treated as infinite!  In other words, electricity is treated as "free" and not costing anthing in terms of fuel. Check out how the math is done

When gasoline is providing the power, the Volt might get as much as 50 mpg.

But that mpg figure would not take into account that the car has already gone 40 miles with no gas at all.

So let's say the car is driven 50 miles in a day. For the first 40 miles, no gas is used and during the last 10 miles, 0.2 gallons are used. That's the equivalent of 250 miles per gallon. But, if the driver continues on to 80 miles, total fuel economy would drop to about 100 mpg. And if the driver goes 300 miles, the fuel economy would be a just 62.5 mpg.

This is entirely consistent with the bizarre way electric cars have always been treated by environmentalists and politicians, as if the electricity is free and they have no  hydrocarbon use or CO2 production.  Which is weird, since we get harangued for our incandescent light bulbs destroying the world when we plug them in but plugging in a whole car does not?

That being said, if one really wanted to move away from hydrocarbon fuels, the smart approach is probably to go with electric cars and then attack electricity generation rather than transportation.  I will feel good plugging in my car because the juice will come from a big honking zero-emissions nuclear plant.


  1. LoneSnark:

    I did the math awhile back and it is more efficient, energy wise, to drive a car on electricity than gasoline. Some coal fired power plants have managed to squeeze 60% efficiency out in terms of electricity production and 80+% efficiency in terms of thermal efficiency (the hot water is used in industrial processes or to heat homes). Meanwhile, even a front-wheel drive car gets only 18% efficiency. This is before you mention that the fuel for the power plant is cheaper than the fuel for the car.

    Which is where the formula breaks down. The price of electricity is not just the price of the fuel, but also the well paid workers required to keep extra plants operating, and the high price of the batteries. Once you include all these, my calculations did not find a payoff at $3 a gallon gas for more than ten years of owning the car, about the time when you need to replace the batteries and start the whole process over again. As such, with my figures owning an electric car never paid off. But it can, all it takes is much cheaper batteries.

  2. Edward B. Boyle:

    Dear Coyote, An interesting aspect of MPG measurement is the competetive trials which were done in te 1940's. Ordinary cars were modified, by such things as shaving all the tread off the tires and leaving a narrow smooth band in the middle, then inflating to 60 psi,.Accelerating from 0 to 15 mph in high gear and then coasting down to 3 or 4 MPH with the engine turned off, and so on. They managed some 75 MPG, which won the contest but was not much use for transportation. Some of the MPG claims made now are almost as bad. In recent years this approach has topped 200 MPG, but is still equally non-useful.

  3. Evil Red Scandi:

    According to Investor's Business Daily, the GAO (in league with big, evil, profit-mongering, planet-destroying oil and coal companies and the GOP) recently released a report saying that if an electric car is powered from electricity generated at a coal-fired plant, the net reduction in CO2 emissions would be 4% - 5%. They further hypothesized that if the "guilt-free" driving would encourage people to drive more, these reductions would be wiped out. Personally, I think the pathetic range / ridiculous recharge times of existing electric cards will wipe out the tendency of people to drive more.

    Whoops, did I say the GAO (in league with big, evil, profit-mongering, planet-destroying oil and coal companies and the GOP)? I meant the GAO under the Obama administration. My bad.

  4. Evil Red Scandi:

    I've noticed in various car reviews from Europe that they list the amount of CO2 created by driving the vehicle. This seems to be a much more useful statistic for people with their panties in a bunch over such things.

    I'm also snickering at the irony of people in California driving electric cars while we, as Dennis Miller put it, buy our electricity at minibar rates (thanks to the spectacular incompetence of Gray Davis and our idiot legislature).

  5. Evil Red Scandi:

    @LoneSnark - Lithium-Ion batteries begin to deteriorate after 2-3 years from the date of manufacture and are almost always completely shot within 3-5 years, as anyone who was ever owned a laptop computer or cell phone can easily attest. Furthermore, they're far from cheap and filled with some extremely nasty chemicals.

  6. feeblemind:

    If I had an electric car, the 'feel good' part about plugging it in would be knowing I was 'cheating' various government entities out of the gasoline taxes that I would not be paying on the electrically powered portion of my trip.

  7. Jim Collins:

    I suggest that you look closer at your electric bill.

  8. James H:

    Is the cycle then set at 50 miles? If so, I just need to build a car that can go the full 50 miles on a charge and claim that you get infinite miles per gallon! Then I could steal away all of the Chevy Volt sales, right? I'd probably get some phone calls from idiot buyers when they are upset about having to gas up on a trip, but I'd already have their money.

  9. Rick C:

    Jim Collins,

    Obviously the trick is to plug in at work.

  10. morganovich:


    you are on to something there.

    i've actually spoken to a number of the battery manufacturers that do the LI bats for tesla and others.

    the tesla batteries are $25k+. let's assume, for the sake of discussion that an electric car's batteries cost $15k. you can get 200 miles on a charge if we are being generous. you will also get about 200 charges worth of life out of the battery before it degrades badly. anyone who has ever had a laptop or cellphone battery go on them knows how steep the deterioration curve is once it gets going.

    so: 200 X 200 = 40,000 miles if you use the cap optimally. $15,000/40,000 miles = $0.375/mile just in battery amortization costs.

    even at $4/gallon gasoline, this is the cost equivalent of getting 10.7 mpg if your electricity is free.

    this is the dirty secret of electric cars: they cost more than a suburban to run.

    the prius battery has a similar problem. i see no reason why the volt would be any different.

    several cab companies in san francisco have experimented with prius's and found that their total cost to operate greatly exceeds a standard cab. an electric car will be even worse.

  11. Matthew S:

    The approach you describe for comparing electric millage to gas millage is nearly identical to the MPGe (Miles Per Gallon Equivilent) being used by the Automotive XPrize. Comparing fules on a gallon of gas equivilent based on energy content.

    From the Automotive XPrize competition guidelines.

    Energy Efficiency (Fuel Economy) – MPGe
    Miles-per-gallon equivalent (MPGe) is a pump-to-wheels energy efficiency figure of merit
    measure that expresses fuel economy in terms of the energy content of a U.S. gallon of
    gasoline. Calculations are based on the energy equivalence of all fuel(s) consumed.
    Basically we ask: how much energy was delivered to the vehicle, and how far did it go? We
    convert the energy to the number of gallons of gasoline containing equivalent energy, and we
    express the result as miles per gallon.

  12. Tim:

    "But one could imagine that one could look at the miles per electrical charge, and then look at the equivalent gallons of gasoline-equivalent BTU’s it took to deliver that electricity, and create an equivalent MPG. In fact, that’s the only approach that makes any sense to me."

    That makes sense, if you are looking to measure miles per energy usage; but that isn't what MPG really gets used for. It's more of a rough measure of the relative efficiency between cars. MPG, or an equivalent MPBtu, is actually a distorting metric, because the scale is non-linear. In other words, a 3 MPG shift from 17 to 20 is a lot more significant than from 25 to 28. The better metric is energy required for distance traveled; Canada shifted to litres per 100 km.

  13. A Friend:

    Morganovich, do you have a link for that SF cab study? I'm curious, since I have a 2004 Prius, and op costs have actually been very low. Oil changes and tires only, nothing else. Battery seems fine so far with 75,000 miles and in CA is guaranteed for 100,000 (I know the guarantee doesn't eliminate the economic cost, just my share.) If the battery doesn't die before the warranty expires, I plan to just drive the car without the hybrid battery until the whole thing dies. Changes the math quite a bit. I've saved thousands in gas, and I assume Toyota ate the cost of the battery install.

  14. morganovich:


    it wasn't a "study" per se. my understanding of this issue comes from asking several cabbies who had priuses how they were working out (maybe 4 or 5 from 2-3 companies) and having 100% of them tell me the co was not going to buy any more as they were too expensive to run, especially compared to the cars fitted w/ CNG engines they ofter use here.

    it also comes from a couple of slides on battery tech from a greentech/cleantech investment conference i recently attended. they listed a dozen or so cab co's that had experimented with hybrids and claimed that all but one has discontinued buying them. new battery tech is, as you can imagine, a hot issue, so a lot of folks are talking about new options, especially batteries that can take on a charge much more quickly. (some techs can do a 40kwh charge in 6 minutes, but these are still in the $40k range, so not ready for most cars just yet and the amortization over 200-250 charges gets pretty egregious)

    regarding the prius - you need to distinguish between miles driven by the car and miles driven under battery power. if you do a lot of driving under engine power, it's irrelevant to the battery. most of your driving probably is gasoline powered, no?
    my neighbor tried driving around in all electric mode (had a plug in version i think?) and had a dead battery in 12k miles.

    my post was predominantly aimed at all electric vehicles, but if the hybrids are going to make mileage claims by assuming they ALWAYS use electric first, then they are going to fall into the same issues.

    of interest, how you drive has a great deal more to do with mileage than what you drive:

    top gear did a track comparison of the prius and the BMW M3 and the M3 got better mileage when pacing a prius being run hard on the track. this also leaves aside the environmental costs to produce a prius, which are much, much higher than most cars.


  15. Flatland:

    I've done a cost comparison using the basic stats for Prius and other comparative vehicles. You may have saved thousands in gas, but compared to similar vehicles you have to drive the Prius at least 200k to 300k miles to make up the difference in capital cost of the vehicle.

    My analysis did not include financing, maintainence, or other miscellaneous costs which would have made things significant worse for the Prius.

    Later, I found out an uncle of mine paid a couple thousand above the MSRP for a Prius. I just shook my head. At least he's blissfully ignorant.

  16. Dr. T:

    The combination of inefficiencies in transmitting electricity, inefficiencies in charging batteries (all the heat from charging is wasted energy), inefficiencies in using battery power, and the inefficiencies caused by carrying heavy batteries within the vehicle make electric cars less efficient than well-built gasoline-powered cars. The only way you can get good utility from an electric car is to reduce battery weight and thereby greatly reduce driving range between charges.

    We can greatly improve energy use by reverting to lighter cars. My 1700 pound 1983 Dodge Colt got 40 mpg city and 48 mpg highway (my actual mpgs, not EPA estimates). No modern gasoline-powered cars come close because they are built like armored personnel carriers (so they can survive collisions with SUVs).

  17. nom de guerre:

    wow. so a government agency has trotted out BS figures showing a car made by government motors gets a billion MPG. this from the same government that doesn't count U-6; doesn't publish M3 anymore; tells us we can give health insurance to 50,000,000 people and it won't cost us anymore than it does already; and assures us that in a month when 247,000 net jobs are *lost*, that the unemployment rate **drops**.

    really, why would any thinking person believe ANYthing they have to say? save time: just automatically assume every word they say and every stat they print is a lie. anyway, who the hell would be stupid enough to buy a chrysler/GM product nowadays?

  18. Michael:

    Fritz Henderson was on the radio today saying the 230mpg rating is 100% realistic for the city driver. Being a radio interview, it was hard to tell if he was serious or just surrounded by armed SEIU members.

  19. ettubloge:

    Just wondering about the safety issues. While MPG are better in this vehicle than my SUV, I transport my children much more safely in the bigger car. Add in the value of interior room, comfort in driving higher, improved visibility, more power, and other reasons I cannot think of right now, the cost per mile is worth incurring in the SUV.

  20. IMN:

    Great article on the GM Volt Nano. I know you can find many more interestnig articles on the automotive industry including who helped Tata build the at http://www.industrial-machinery-news.com

    Thanks for the information


  21. Doug:

    I dug up the specs on the Volt yesterday from GM's webpage. It's a 16 kWH Lithium-Ion battery, as opposed to the Prius Ni-MH composition. The latter are "yesterday's technology," albeit a mature technology. When I was looking at the Camry hybrid a couple of years ago, I read an interview with Toyoto's head of battery technology in one of my trade rags. I found it hard to believe when he said then that they had yet to experience a SINGLE battery failure in their battery packs, which is why they are guaranteed for 75k (?) miles. Quite an accomplishment, if true, especially since they use Ni-MH cells, whose cell life is notoriously bad.

    The energy rating of this Volt battery got me to thinking. You have to be very careful when charging a Li-Ion battery. They can create some VERY nasty fires should they ignite. (Just ask Apple, Inc.) Thus, the charger requires some elaborate circuitry (called constant-current/constant-voltage, or CC/CV), which involves power losses during the charge cycle. If you get serious about the design, your charger might be 80% efficient. Thus, to charge my 16 kWH battery will consume 20 kWH of energy. (kWH is energy, kW is power, the derivative of energy.)

    GM says that the battery can be charged in 3 hours @ 220V or 6 hours @ 110V. I am assuming most people who just want to plug 'n go don't want an electrician visit to rewire their garage/charging station for 220VAC, so the average bugger is going to go with the 110V charging option, and need 6 hours to fully charge his wheels. That's 3.333 kW/hour. Or about 28 amps of power from your plug. Don't try this at home with your 14 gauge extension cord, kids!

    I looked up the electricity rates from my power company and see that they're going to hit me for about $.14/kWH (no time-dependent rates where I live). So a "full tank of gas" in a Volt is going to cost me about $2.80, ±. $2.80/40 miles = 7¢/mile. My fully-loaded Toyota Camry V6 can gets about 25 MPG, or about 12¢/mile.

    I fail to see where the win is in this math. As others are pointing out, that electrical energy has to come from somewhere; more than likely from some coal-powered plant in AZ, since CA won't build any more power plants. How the hell is this going to reduce CO2 emissions?

    Lastly, Li-Ion batteries have to be babied to get the most life out of them. Don't charge them when they're too hot or too cold; you even have to scale back charging when it's just chilly to preserve the life of the battery. The Volt is also no doubt going to do the same thing that the Tesla folks do and NEVER fully drain the battery. Doing so is a very good way to significantly reduce the number of charge cycles you can get from the battery. So while your battery may be rated at X KWh, you can only extract X/2 KWh from it before the on-board computer says "that's all, folks!"

    Smart Li-Ion battery handling is how Apple (claims to) get 1000 charge cycles from their Macbook batteries. I can testify that it is true. Perhaps the Volt does the same thing. Brainless battery charging, as is routinely practiced in the PC world, is the reason for their crappy battery lifetimes. If those clowns had to actually DESIGN something, then they might end up with a better product.

  22. Christoph Wienands:

    Now for all the people complaining about the electricity transmission loss, losses duing charging, etc. , let's not forget that refined gasoline does not just magically appear in our cars' tanks.

    Rather, crude oil needs to be pumped out of the ground, pumped sometimes a couple hundred miles to the next port, put on big, polluting tankers, then it gets refined, and finally carried by truck to you neighborhood gas station. All this requires energy, similar to losses with electricity.

    Now, of course fossil fuel power plants also need fuel, but I would dare say with 50% of electricity produced from coal, that the losses are not as great as for gasoline.

    I believe that electricity is THE universal energy currency of the future, and obviously electric cars can use it. Rather than sticking with gasoline-fired engines based on 100 year old technology and doing tricks to produce bio fuels, it will be much, much easier to use electric cars and gradually shift electricity generation from fossil fuels to renewables, such as PV or wind.

  23. D G Arthur:

    The costs can be manipulated to show many things. Whether or not the Volt pencils out for accountants and green warriors isn't the key. If it sells it and if it is preceived as good will be the key.

    Hopefully this is a step in progress toward true efficiency in all areas - from manufacturing to usage. Over the past 10 years there has been great improvement in battery life, efficiency and alternate power sources (solar). If GM et.al. is able to put money into R&D and continue making improvements there maybe a future for electric cars.

    The best way to make this work is not a rebate (money out from the government) but a significant gas tax increase (money to government - roads, R&D, ...).and proven "green" benifits.

  24. Bob Durtschi:

    Christoph Wienands: much easier to use electric cars and gradually shift electricity generation from fossil fuels to renewables, such as PV or wind.

    Until you look at the actual numbers as was done here: http://denbeste.nu/cd_log_entries/2002/07/Carbonemissions.shtml

    "In 1998, the State of California consumed 13.496 billion gallons of gasoline. A gallon of gasoline yields about 130 million joules. So when you do all the math, you end up with about 1.755 * 1018 joules, which is an impressively large number.

    One anti-solar-power advocacy site gives the "yearly average" solar power density in Albuquerque as 240 watts per m2. (That appears to be a 24-hour average; another site says that it's 700 watts in daylight.) Then presuming that southern California is similar, each square meter of mirrors would be struck by 7.573 billion joules per year.

    So if you assume 100% conversion, you'd need 231.7 million square meters of collection mirrors to make this work. 231 square kilometers.

    But it isn't going to be 100% efficient. That's impossible, and it isn't going to be remotely close to that. The mirrors won't reflect perfectly and some of the sunlight will heat the metal instead of reflecting. The conversion process into hydrogen will be extremely inefficient. If you get 10%, you'll be doing really well.

    So we're talking about paving 2300 square kilometers of California desert with mirrors. That's a strip 13 kilometers wide stretching from San Diego to Los Angeles. It's an area twice the size of San Francisco.

    That's a hell of a lot of metal! It ain't gonna be cheap. The capital expense involved would be mammoth. Just clearing an area that large would cost a fortune; paving it with manufactured goods will cost a fortune. And something that big would take decades to build.

    Figure each mirror at 10 square meters, and you're talking about 23 million motor mounts. If you figure an average 5 year lifespan, then you're going to replace more than 4 million of them per year.

    . . .
    By the way, forget about photo-voltaics. They are also about 10% efficient, and they're made of silicon. The idea of paving 2300 square kilometers of desert with solar cells is even more ludicrous; there isn't any way that industry could approach that kind of volumes anytime soon. (If they're producing a million square meters, one square kilometer, per year now I'd be very surprised. I bet they aren't even producing ten thousand square meters.)

  25. A Friend:

    Thanks, Morganovich.

  26. bluemonkey:

    The battery pack itself, rated at 16 kilowatts/hour, comprises more than 220 separate cells wired in series. That means the failure of any one cell disables the entire array, though some existing hybrid vehicles also have this flaw. The Volt pack is about six feet long and weighs a hefty 375 pounds.
    Voltage: 320 – 350 V
    100% recharge time:
    110V outlet: 6 – 6.5 h
    Electromotor: 45kW
    GM also claims the 2011 Chevrolet Volt can run solely on electric power for 40 miles with a full battery charge. That’s in line with studies showing that most Americans drive only about 40 miles a day, so in theory at least, a Volt could go for weeks without using a drop of gas or spewing any CO2. But some analysts think the real-world electric range will be closer to 30 miles and probably less, depending on vehicle speed, ambient temperature (which affects battery performance), and whether trips include steep grades.
    After how many recharge cycles (DAYS) the Battery Pack 16KW/H with 220 separate cells wired in series, weighting 375 pounds, HAS TO BE REPLACED WITH A BRAND NEW ONE?
    If this car will be used as a normal hybrid car:
    If the battery pack is fully charged overnight, the fuel tank filled with gasoline (gasoline pump shuts off) and the car is driven non stop 230 miles: