Don’t Be a Dolt, Buy a Volt


Wait a minute, a car that gets 230 mpg in the city—as claimed by General Motors? Well, you’ve got to read the fine print, Jack, as the story has gotten played out all over the web, courtesy of GM’s press machine.

Is it too good to be true? The Environmental Protection Agency hasn’t verified the claim, as it hasn’t actually tested the Volt. And there’s debate about EPA’s testing procedures, its conclusions, and most of all, its methods for rating plug-in hybrids, or EVs. The agency is still working on the methodology, but there is much skepticism afoot. Check out the story and comments here on the Car Tech Blog, for example.

The Volt, as you may remember, has a 100-kilowatt electric motor, a lithium-ion battery to power it, and a 1.4-liter gasoline engine driving a generator to run the electric motor as the battery discharges. You plug in at night for a complete battery recharge at minimal cost. But—and it’s a big “but”—the car will cost at least $40,000, and you can buy a lot of $3.00 gas for the difference between that and a Prius’ cost. Someone calculated you would have to drive 113,000 miles to make up the price difference. And there are other factors.

Autopia mentioned some of these, quoting a former Tesla exec (no axe to grind here?) who talked about the difficulty in measuring “energy equivalents,” e.g., batteries, house current, power losses, gasoline—not to mention driving cycles. The Volt can run 40 miles before the engine kicks in, so if your commute is less than that, you’ve achieved infinite mpg, not counting use of other resources. Well, that is impressive.

The Tesla exec, Darryl Siry, says in his blog that GM’s 230-mpg claim

isn’t an “untruth”, as long as the main thing you are concerned about is the burning of gasoline as a resource, as opposed to the actual energy efficiency of the system. The problem is that this number will be broadly discussed as a comparison to other cars, particularly the Prius. People will improperly conclude that the Volt is about 5 times more efficient that [sic] the Prius, which simply isn’t true.

So why is GM making so much noise about its admittedly impressive but unverifiable estimate? Well, to co-opt the Prius, of course. And Siry is right when he says it’s also because of the increasingly demanding CAFÉ standards. GM will get a lot of mileage off their 230-mpg claim, even as it’s challenged.

Is the Volt’s claimed 230 mpg more GM marketing hype—or something to celebrate? Let us have your opinion.



  1. Yeah well, I think you need som brushing yourself because dividing by zero doesn’t give you zero. You just can’t divide by zero. There’s no mathematical law that allows you to do so.

    However if you calculate y = lim x->0 miles/x where x stands for gallons. You get y->infinity

  2. “The Volt can run 40 miles before the engine kicks in, so if your commute is less than that, you’ve achieved infinite mpg, not counting use of other resources. Well, that is impressive.”

    Infinite MPG? Brush up on your arithmetic. MPG = miles/gallons. Anything divided by zero is ZERO. Don’t feel too bad though, much more prominent members of the press failed math too. (As well as quite a few guys with big financial degrees.)

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