back to article Men in Green step back from GM's 230mpg Volt claim

The US Environmental Protection Agency has cast a shadow over General Motors' bullish claim that the Chevy Volt - aka the Vauxhall Ampera - can do 230 miles on a single US gallon of fuel. In a statement released last night, the organisation said: "The EPA has not tested a Chevy Volt and therefore can't confirm the fuel economy …


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  1. Paul Murphy 1

    My use would be..

    Unplug and drive 25 miles* or so to work,

    plug in again,

    unplug, drive back home and plug in again.

    x 4 for the rest of the week

    At the weekend it would be a few local trips, probably not exceeding 30 miles total per day and then plug back in.

    Occasionally we would be travelling further, but by far the most time would be around 'short' trips which would not use fuel.

    How to get an agreed measure on economy would be tricky, but at the end of the day I am more insterested in a car that can travel at, say, 60mph for 30 to 40 miles before being recharged or using it's engine.

    I suspect I'll have a long wait.


    *should be around 15 really, but London traffic doesn't equate to straight-line driving.

  2. Anonymous Coward
    Anonymous Coward

    Miles per kilogram of coal

    Maybe figure how much power is needed to charge the car... or how much coal will need to be burned to charge the car. We have enough rolling blackouts on the west coast from people using too much power. I'm waiting to see what happens when enough people own electrical vehicles to really stress the grid.

  3. davefb

    they're not real world already

    So while we're at it, can we 'fix' the current ones?

    As in, since they're done on rolling roads, there's no actual input from wind resistance.. Or am I wrong in this??

  4. kevin mulholland

    proper figures

    Why not report how far you can go on a full charge and a full tank, without any recharges and of course report the tank size, so we can judge for ourselves how useful an overpriced hybrid car would be.

  5. Tony Smith (Written by Reg staff)

    @Kevin Mulholland

    When we get behind the wheel of one of these boys, we will. Watch this space...

  6. Cameron Colley

    Or forget "Miles Per Gallon" entirely.

    Unless the car charges from a wind turbine then "miles per gallon" calculated like this is utter shit and anyone spouting this is an idiot or a liar, or both. There is no one-formula-fits-all and plugging the car in does not men it has used no "Carbons" or, more importantly, that it has not cost you any money.

    The figures needed are Miles per KWH when under electric power, the range of its battery, Miles Per gallon when using Petrol and the amount of petrol needed to charge the battery. With some knowledge of your weekly driving you could then, if you wished, calculate its "Carbon Footprint" or its cost to you for an average week.

  7. The BigYin
    Thumb Down


    "The existing ones make no sense when applied to a car which can technically achieve an infinite number of miles per gallon as long as you never venture more than 40 miles from a power socket."

    Balls. Total and utter balls. The power has to come from somewhere. It would be trivial to monitor how much juice was fired into the Volte batteries during charging and back-calculate the resources used at the power station. This should then be included in the l/100km figure (not mpg as we are now in the 21st century...well some of us are).

    Leccy tech may not pollute as much in the city, but it sure as hell pollutes at generation!

  8. Anonymous Coward
    Anonymous Coward

    60MPH on a 1.4L Petrol..

    ... charging a battery and running at optimum revs/efficiency... Surely should be much much more.

    Interestingly though it's going to create some odd scenes - say you havn't charged for a while and are therefore charging from the engine. Parked at a traffic light with the engine running at 3000rpm.... while the BMW/Audi/whatever has automatically shut it's convential engine off next door....

  9. JRS

    Alternative MPG

    For the purposes of calculating MPG for electric/hybrid cars, just make each recharge come from a petrol generator. The manufacturers have to get as many miles as possible out of just one gallon of fuel with which to power the car either by direct burning in the cars engine or via the generator.

    The alternative is to have a standard cost per mile for petrol / diesel / grid electricity, and price up a standard weeks travel in each vehicle.

  10. Paul Barnfather


    Wind resistance is taken into account using a coast down test:

    It still doesn't help the published figures get anywhere near real-world driving.

    Unfortunately there are many {ahem} tweaks that manufacturers can make to influence the results of the coast down test and hence get much better mpg/CO2 figures...

  11. Richard 102

    Is coal clean?

    The enviroweenies won't let us use nuclear, they hate burning oil and gas, wind is way too inefficient, building hydro-electric dams hurts the fish, geothermal and solar aren't highly scalable, ... and that leaves coal or burning wood. This is better?

    For all the problems with petroleum, it's cheap (certainly cheaper than milk or bottled water or soda or beer), efficient, has the infrastructure already, and is a known technology.

    I think the real problem is that oil companies make money, and profit always seems to make lefties twitchy.

  12. Time for a career change
    Thumb Down

    Why petrol engines?

    When diesel engines can easily give more mpg and power per cc, why do manufacturers of hybrid vehicles always dump a petrol engine in their models?

  13. Anonymous Coward

    Consumer Reports is also debunking this claim

    Consumer reports mentioned that the mileage claim was off, questioning the methods used to come up with the 230 mpg figure.

  14. Matt 13

    fill the tank....

    surely mpg/mpcharge should be measured as distance travelled without stopping... if the mpg claims are made with the car being recharged every 5 minutes then they are a waste of time...

    a move away from mpg will be needed and miles per unit of energy will be needed... a comparable approximation of the cost of running an internal combustion engine + cost of charging a battery pack = overal cost of driving/cost to environment, this way an SUV with a tiny hybrid engine to bend its way into 'green tax bands' will still be less environmentaly sound than a small capacity compact diesel car...

    while we have it, there should also be an Xyear/Xmiles TCO figure laid out - environal cost of raw production, transportation to dealer, replacement batteries, disposal + recycling to really force the car manufacturoers to not hide behind ludicrus mpg and buzz technologies, but to show commitment to the environment....

  15. Ray0x6


    the way to do it is to not count charge taken from the grid. you should only count the electricity generated by the petrol engine used to charge the vehicle's battery. otherwise, you could clearly go as far as you wanted on no gallons of fuel at all, simply by getting to a power point before your battery goes flat.

    people seem to forget that electricity from the grid is not necessarily cheaper or greener. in fact, it is probably much less efficient than that generated by an optimally tuned petrol engine running at its most efficient speed. gcse physics says that v = ir and there's some serious resistance on those hundreds of miles of copper wires going from the power station to your house, meaning that the current you receive is only a fraction of that which is generated, unlike in your car where you'll get almost all of it. the maths is not difficult but it is inconvenient for people with an agenda to push... that is why i doubt the EPA's methodology takes any of this into account because it will obviously make business look bad.

    sorry to be such a party pooper but there is so much 'green' bullshit out there that simply doesn't stand up to even basic thought experiment and i fscking hate it.

  16. JCF2009

    EPA's proposed standard for electric/hybrid vehicles

    A version of the proposed EPA standard, that may have been used by GM to come up with the 230 MPG figure, has been published at:

  17. Matt 32


    >When diesel engines can easily give more mpg and power per cc, why do manufacturers of

    >hybrid vehicles always dump a petrol engine in their models?

    There is not a direct trade off between how much diesel and how much gasoline a given barrel of oil can produce. While the exact ratio varies depending on where the oil comes from, and refining can favor one or the other a bit, when you look at how much diesel and gasoline can be made from a barrel, a significant part will be gasoline.

    Since you have to burn the gasoline somewhere, using it for lower compression (i.e. lighter weight) engines for hybrids is a good use.

  18. Anonymous Coward

    @Time for a career change

    because Diesel engines are much heavier than petrol and are more difficult to control in a start/stop configuration ?

  19. Paul Barnfather


    "...unlike in your car where you'll get almost all of it"

    Umm, nope. According to the US DoE you get "about 15%".

    Perhaps you've forgotten how inefficient modern cars really are? A good engine only manages around 30%. That's not "almost all".

    Compare that with a battery car:

    Fossil fuel power stations are 36-40% efficient. Power lines are about 90% efficient. Factor in battery charging (97%) and electric motor (92%) and you get 29-32%. No brilliant either; about the same as a fossil fuel powered in fact.

    Thing is, we already know we can get vast amounts of electricity from nuclear & wind. So we might as well see if we can use some of it to power our cars...

  20. Pete Smith 2

    @Time for a career change

    Modern common rail diesel engines run on diesel, and diesel alone. Biodiesel, SVO, RVO etc will shred their high pressure diesel pump innards, due to not being lubricating enough (fnarr). The pressures that these pumps generate is insane. I've seen over 28000psi on mine (via its ODB connector)

    Diesels aren't allowed in certain Japanese cities (but that seems to be changing now) with improvements in the particulates. Diesel has (AFAIK) never really taken off in the USA, and is (AAIU) not possible to buy a diesel car in California due to emissions laws. If you're trying to sell into Japan and USA, you've got to use a fuel that's allowed and popular.

    Petrol engines can run on petrol, alcohol, LPG, CNG, Hydrogen etc. They're also smaller, lighter and quieter.

    I'm not prejudiced against diesels BTW. I've got a 2 litre turbo diesel myself, and wouldn't go back to petrol without a really good reason (such as that 2.9 V6 Cosworth Scorpio, full leather interior and LPG conversion for £450 I didn't get) .

    I'm hoping that my next car will be a plugin hybrid with min 40 miles range (enough to get to work to charge up)

  21. Timo

    why not claim infinite gas mileage

    Why doesn't GM just quote gas mileage when driven in 40-mile segments? You drive 40 miles, pull over, plug in, wait X hours, then drive 40 more miles. Zero gasoline used, gas mileage = infinite!!! Sure it might take you a while to get there but hey zero consumption is technically possible.

    Marketing BS.

    Alternatively they could get infinite mileage if you just hitch a Volt to the back of some other vehicle. In fact this is possible today with ANY VEHICLE!! My god I could claim that my Honda Civic (which already gets good mileage in town) is possible of ZERO CONSUMPTION or INFINITE GAS MILEAGE!!!! Now who wants to get onboard when I push this out for IPO!?!?!

  22. Sean Timarco Baggaley

    Consistent metrics are important.

    (Just found this, btw: — it's a recent paper; has it been covered in El Reg?)

    There are two main types of car: single-power types (e.g. petrol only, diesel only, electric only, etc.), and the dual power / hybrid power type.

    For single power-source vehicles, the most useful metric is:

    "Total Range@[x] km / hr. on a full tank / charge".

    * The cost of providing that energy represented by that tank or charge is also noted. (This gives a comparable metric across the different types of battery, be it a Li-Ion or "tank of petrol". Both are just a form of energy storage.)

    * Another key point here is that two figures need to be quoted: one where [x] is the typical national *urban* speed limit (approx. 50 kph in the UK) and the second where [x] is the typical national *extra-urban* speed limit (approx. 100 kph in the UK). This mirrors the current practice of similar figures for urban and extra-urban usage, with a combined average figure also shown.

    The upshot of which would be an idea of how far you could go before you need to replenish the energy store, and how much that replenishment would cost you. For salesmen who tend to do a lot of long-distance driving, the extra-urban figure is of most interest; for city runabouts, which aren't meant to be used for anything other than local travel, the urban figure would be more prominent.

    This gives a single, consistent metric across all forms of motive power. A battery is just a tank for electricity; that you have to charge it rather than refill it is irrelevant. It's just an energy store, like petrol, diesel or LPG. That energy has to come from *somewhere*, and it will cost you money.

    The sticking point will be "cost of replenishment". Depending on how your electricity is generated, this can vary wildly for electric vehicles from nation to nation. The French have lots of nuclear power stations; the Swiss tend to prefer hydroelectricity; we Brits have rather more fossil fuel supplying our grid. (The US' power generation pattern follows a similar one to the UK, mixing some token carbon-neutral generation with a heavy reliance on fossil fuels.)

    This means each country will also need to publish an annual, average cost per kWh and similar figures for other energy sources. This would give manufacturers a standard by which to show how much their cars will generally cost you to run.

    Thus, for a hypothetical electric-only FIAT 500 wrapped around a Li-Air battery stack (see link at top), you'd see something like:

    1600 km. @ 50 kph. (Li-Air Cell, cost for full charge / cartridge swap £5.00)

    You can read that as: "£5 for a full tank which gets you 1600 km. of travel if you're driving at roughly 30 miles per hour." (The FIAT 500 is a very small city runabout car, so you wouldn't want to put big batteries or motors in it. It has little enough boot space as it is!)

    I suspect that electric cars will take off almost overnight in countries like France, where most electricity is already produced by nuclear fission. As nations start to move away from fossil-fuel power generation—a process which can take generations—we'll see petrol and diesel slowly becoming marginalised, until it's only found on a few specialised vehicles, such as some military, farm and construction machinery.

    (I'm in favour of more fission plants here in the UK. They're not perfect, but they're better than burning coal, gas or oil, all of which can be put to far better, more constructive, uses. Fission is a stopgap, buying time for researchers to sort out a better replacement. Which might be fusion, or might turn out to be something else entirely. Such as an emphasis on micro-generation.)

  23. Martin Lee

    MPG Depends on

    how long your extension cable is.

  24. Anonymous Coward
    Anonymous Coward

    I'm with El Reg

    What all this fuss?

    An MPG measure is for fuel economy, that way I can estimate (assuming a comparable driving pattern to the test standard) how much it is going to cost me to buy FUEL for the distance that I drive. I incur other costs as well and those need to be considered when I buy the car (only and idiot would just look at the MPG - reg readers are a pedantic lot and are most likely to consider the details)

    You don't expect the MPG of the truck that pulled your fuel to the petrol station to be considered when I think about an ICE vehicle* why are we talking about power stations (they incedentally have a REALLY bad mpg measure of 0)?

    If we want to talk about a "geen" measure then lets have a flame about the CO-2/[unit of distance] numbers and include the powerstation, lets also include the carbon foot print of production, that will be fun exploration of the issues and enlighten us all.

    Surely all we can say if you bought this car, and you drive in an urban environment then you will probably spend alot less on fuel, (you will pay more in electricity though)

    *would it be anti-green to call petrol/diesel cars ICE'icles?

  25. Marc 1

    Calculating 'background' costs...

    If people are going to go the route of calculation the fuel needed and pollution generated in the supply the electricity to charge one of these cars - it would only seem logical to calculate the costs and pollution generated to refine and transport fuel for a gasoline powered car too..

  26. Anonymous Coward
    Anonymous Coward

    @Paul Barnfather

    I suspect your efficieny numbers are skewed in favour of the ICE vehicles... If you include the efficiency of the distribution network for electricity, what is the argument not to include the efficiency of the fuel distribution network?

  27. Andy Bright

    50 or 5000?

    The Chevrolet Volt runs on electricity that comes from two sources, a battery as well as a petrol engine.

    When petrol is providing the power, the Volt is supposed to get about 50 mpg (US gallons are smaller than UK gallons so I reckon that equates to about 60-65mpg in Britain).

    Anyway if the car is driven 50 miles in a day, for the first 40 miles no gas is used. During the last 10 miles, 0.2 gallons are used, which is the equivalent of 250 mpg.

    The way Chevy tells it is 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 just 62.5 mpg.

    They imply that it would perfectly reasonable for a driver to travel 300 miles without needing to charge it up. Because if it was charged, why would the fuel economy drop over distance?

    So my guess is that this isn't a normal electric car, instead it has more in common with a hybrid.

    They also admit that first time adopters aren't going to save any money, as the cost of the car is going to be about $40,000 but would qualify for a $7500 tax rebate that dealerships generally work into the sales price. What they might do is subsidize the cost of the first few thousand cars, hoping that with enough volume, the price of building it (also $40,000) will fall. It isn't unusual for car manufacturers in the US to sell cars at a loss, in fact it shouldn't surprise anyone given the mess they're all in.

    Even with the rebate that's at least $10,000 over the price of something like a Toyota Camri, a larger car with a pretty decent mileage of its own, especially if you buy the hybrid version. $10,000 buys a lot of petrol, even in Britain.

  28. Mike 61


    MPG is not the measure *I* am interested in, what I would be more interested in is TCO and miles per dollar (or kilometers per euro). I spit on carbon emissions and global warming, I want cheap. Until then they can take their eCar and shove it in the appropriate socket...

    mines the one with "nuke the whales" on the back.

  29. wengelke

    Recharging will always be an issue

    When recharging is used, EPA's current mileage formulas are clearly inapplicable. What might be better would be to show mileage per BTU of energy used, which you can calculate for all fuels as well as electricity used for charging. What everybody in the electric car frenzy forgets about is that these vehicles, great as they are, will put lots of additional load on the electrical grid - a load that many experts say needs to be reduced (not increased), as electrical generation is a major source of greenhouse gases, coal ash, nuclear waste, and other pollutants. Electric and hybrid cars are great but are only a part of a total energy solution.

  30. Stevie


    In New York neither Con-Ed (NYC power company) nor LIPA (Long Island Power Authority) have proved capable of keeping the juice on 24 x 7 with the current (haha) domestic power requirements, especially during summer.

    My question is: how the bloody hell will they manage when everyone and his dog has a car plugged in every night in addition to the same stuff they use now?

    My next question is: Who gets thrown to the wolves when the required 8-hour overnight charge isn't do-able and everyone finds themselves doing 22 to the gallon like before?

  31. Al Jones

    @Rolling Blackouts

    "We have enough rolling blackouts on the west coast from people using too much power. I'm waiting to see what happens when enough people own electrical vehicles to really stress the grid."

    How many rolling blackouts do you have at night? On the US West Coast they usually occur during the middle of the day when air conditioning is at full blast and office and industrial customers are generating peak demand.

    Overnight charging of electric cars isn't going to put much strain on the electric grid, and in some scenarios, specialised charging points will be able to suck charge out of parked and tethered electric vehicles at peak times, smoothing over the peak demand, (when marginal rates for the last few kilowatts run into the hundreds of dollars instead of the pennies the end user actually pays).

  32. Stephen W Harris

    Math is hard, let's go drinking

    "GM has said that the EPA methodology uses kilowatt hours per 100 miles travelled to define the efficiency of plug-ins, and that GM expects the Volt to consume as little as 25kWh per 100 miles in city driving."

    Petrol has an energy density of around 32MJ/liter (wikipedia), which is 8.45MJ/gallon (US gallon=3.78liter), which is only 2.3kWh (1 megajoule ~= 277 watt hours) of energy. So that sounds like it actually does less than 10mpg when running on the internal generator.

    Umm... is my math wrong?

  33. Charles Manning

    re:Why petrol engines?

    Ignorance. Not manufacturer ignorance, but amongst the customers.

    These machines are more about perception than real saving and the numerically illiterate also think that diesel is dirtier (from seeing too many sooty truck tailpipes). Therefore a petrol engine is used to improve the clean air image.

  34. Peter Bond

    Energy use

    Interesting that nobody is suggesting that conventional MPG figures (or the energy used by petrol driven cars) should include a weighting to allow for the energy expended is extracting, refining and transporting petrol to the pump. The energy required to generate electricity shouldn't be left out of the equation, but nor should the true cost - in energy terms - of getting a gallon of unleaded into the tank.

    @Ray0x6 - surely the EPA figures are intended more as a way to compare Car A with Car B on a level playing field than as an absolute definiton of fuel or energy consumption. Whatever test system the EPA cooked up someone was going to start whining, but some sort of methodology is needed to compare a Volt with a Prius plug-in with a Mitsubishi plug-in in order to give Joe Public some sort of idea which will be the cheapest to run.

  35. Steve Martins

    my 2 litre kettle...

    can produce 20 litres of tea (and up to infinity) as long as i keep topping it up! so the manufactureres should surely have told me its a 20 litre kettle? better would be a miles per (charging) hour figure i.e 3MPcH + 60MPG then the figures would reflect the truth.

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