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GM and EPA team up for new fuel economy label for the Chevy Volt


November 25, 2010

The new label provides relevant information for buyers of EVs and hybrids

The new label provides relevant information for buyers of EVs and hybrids

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With hybrid and electric vehicles appearing in more and more automobile showrooms around the world, the traditional fuel efficiency measure of miles per gallon (MPG) alone just doesn’t cut it anymore. With cars able to be powered by electric power alone or a combination of electric and gasoline, new measures are needed to better inform consumers when buying a new car. To this end, General Motors (GM) and the Environmental Protection Agency (EPA) have teamed up to design a new window label for the Chevrolet Volt that has more information than any EPA label before it.

To make the fuel efficiency of alternative fuel vehicles easy to compare to traditional gasoline-powered cars, the MPGe measurement has been widely adopted. This stands for miles per gallon equivalent and is determined by measuring the electricity use (kilowatt-hours) of the vehicle and converting it based on the energy content in a gallon of gasoline. The EPA calculates the MPGe based on a conversion factor of 33.7 kW-hr of electricity being equivalent to the amount of energy in a gallon of gasoline.

When driven in electric mode, the new label lists the Volt’s fuel efficiency as 93 MPGe, while the combustion engine provides a fuel efficiency of 37 MPG. Both figures were determined by the EPA using a combination of city and highway driving. A combined composite figure for overall fuel efficiency of 60 MPG is also displayed. The 93 MPGe figure is much lower than the 230 MPG GM was promising a year ago but the company says this is because that figure was reached using a draft proposal for rating EVs that the EPA later rejected.

The label also displays a range of 35 miles in electric mode for the Volt, (GM claims a range of 25 to 50 miles – depending on conditions), and a total range of 379 miles possible when switching to the combustion engine once the batteries are flat. There’s also how the vehicle compares to other cars in its class in terms of overall MPG, greenhouse gas emissions and other air pollutants, as well as charging time and estimations of how much it will cost to run the vehicle in a number of different driving patterns.

By way of comparison, the all-electric Nissan LEAF received a rating of 99 MPGe, while the long time fuel economy leader, the Toyota 2011 model Prius, received an overall rating of 51 MPG.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

For cosmetic reasons, the Volt will have a lower MPGe figure than Nissan\'s Leaf. Had they smoothed out all exterior surfaces, enclosed the wheel wells, and added a boat tail--all at zero cost--they would have won this contest.

I am not in the car business, but people will buy the entire output of the Volt production line for several years no matter what it looked like. Why didn\'t GM lead instead of following other followers? Costly \"styling\" diminishes aerodynamic efficiency.


It is just me that thinks a petrol engine is stupid. Why on earth did they not use a diesel engine - if the POLO blue can reach 80mpg of its diesel engine - what on earth are they doing with a 34mpg petrol engine. When will they fully embrace this concept fully and actually design a high efficiency generator engine and actually get the magical 200mpg that should be the target.


Actually, they should be using a very small (high weight to power ratio) turbine engine. Around a hundred years ago, Nikola Tesla, the guy who nearly single-handedly invented the first part of the twentieth century, invented a bladeless turbine that\'s cheaper to make than the bladed turbines used in jet planes. Tesla never sold many of his turbines after patenting them in 1913 because materials science wasn\'t capable of producing the blades cheaply enough to make this a breakthrough technology. But we\'re there now.

Another old but appropriate technology for the Volt is the Stirling engine, invented nearly 200 years ago (1813) by Robert Stirling, a Scottish inventor. The Stirling engine is an external combustion engine so no explosions, more controlled burning, less moving parts, and more efficiency than a reciprocating engine. The problem with Stirling engines is that its power output isn\'t instantly adjustable, but that wouldn\'t matter with a Chevy Volt because the engine just charges the batteries. The electric motor/generator is the actual primary mover of the Volt, and the power output of that is instantly adjustable by the driver.


The choice of \"petrol\" engine over diesel (the logical choice) probably has as much to do with marketing as the un-aerodynamic exterior design elements; I also suspect it has to do with meeting emissions goals.

William Lanteigne

The write says that \"the MPGe measurement has been widely adopted\". He should qualify that with \"in the USA\" since it does not have much relevance anywhere else. Nobody else has ever used US gallons anyway! The idea of having an energy equivalent to bridge the transition from fossil-fuel to electricity is probably a good idea as it would help the consumer understand the differences and therefore better buying decisions. However any units used would (ideally) be universal and therefore based on the standards that are used by some 95% of the world. It is time to lose the HP/PS and move to watts which is indeed a universal measurement. As a trade-off though how about also losing the strange \"litres per 100Km\" and use instead \"Km per litre\" which would be easier to adopt for the millions of people using MPG ?


Lets see, the Chevy Volt gets 35 miles on a charge, the Aptera 120. The Volt performance similar to a small gas powered car, the Aptera 0-60 in under 11 sec. fully loaded with two passengers and luggage. Top speed of both cars about 95 mph. The Volts fuel equivalent efficiency about 95 mpg, the Aptera at least 150 mpg. Price of the Volt $41,00 MSRP, estimated price of the Aptera H2 $25,00-$30,00. The Volt produced by a multi-BILLION dollar company with one of the largest most advanced design labs in the world, Aptera, a multi-million dollar company with one of the smallest design labs in the world! Chevy, backed by the U.S. government, spent $1,000,000,000 (that\'s BILLION) dollars to develop the Volt, which it will sell at a loss! Aptera spent several Million Dollars to develop the Aptera, so far with ZERO government assistance! I\'ll take the Aptera!

Jerry Peavy

Our Governor, Linda Lingle (Hawaii) has just announced that she will be receiving her LEAF this Sunday (Nov. 28). Three hundred more will be coming in Dec. and the early part of 2011 for customers who have already made pre-payment.

I agree completely with TogetherinParis in comments on how the aerodynamic qualitities of the Volt could have been improved.

We in Hawaii, especially for the people of Oahu where range is normally not a critical factor, hope that the LEAF will prove valid and sustainable daily transport.

Adrian Akau
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