Picture copyright GM
A twitter account claiming to be General Motors has been making vague statements about the number "230". It's started a fair bit of speculation about what the heck they mean by "230" and today GM revealed the news behind the "230" teaser. Namely that "the Chevrolet Volt extended-range electric vehicle is expected to achieve city fuel economy of at least 230 miles per gallon, based on development testing using a draft EPA federal fuel economy methodology for labeling for plug-in electric vehicles." This is a pretty jaw dropping fuel efficiency that's made possible by the onboard electric motor system. Now the speculation going around the tweetosphere is in the "what the <censored>" line of thinking in how they achieved such a high fuel efficiency.
Before we start looking into GM's claims it's worthwhile recalling the fuel efficiency claims of some electric cars. Nissan claims their recently LEAF has 367 MPGe and in the past Tesla Motors claimed the Tesla Roadster to have 170 MPGe efficiency, but that claim appears to not be on their website any longer.
Obviously electrons do not come in gallons and to make a "miles per gallon" claim for an electric car requires some conversion factors. The Volt however is a plug-in hybrid rather than a pure electric car, which makes the calculation of fuel efficiency even more difficult. The calculations must take into account average driving patterns with electric only mode and gasoline assist mode.
GM Chief Executive Officer Fritz Henderson said "The key to high-mileage performance is for a Volt driver to plug into the electric grid at least once each day." Obviously when the Volt is driving in gasoline mode its fuel economy is the efficiency of the gasoline engine, and while driving in electric mode it's the relative efficiency of the electric motor. Because electric motors are more efficient than gasoline engines a driver whose driving makes more use of electric mode will achieve greater overall efficiency.
The Volt is claimed to have a 40 miles electric only range. Drivers who can stay within that range could conceivably never have to buy gasoline. But if they want to never buy gasoline the LEAF may be a better purchase given its longer range.
The 230 MPGe number is based on early tests using draft guidelines from the U.S. Environmental Protection Agency (EPA). The actual number is of course subject to change by the time the Volt truly goes on sale, because the EPA may change the rules and GM may make changes in the Volt design. At the moment GM is touting this as the first mass produced vehicle to achieve greater than 100 miles/gallon efficiency.
Subscribe via: Facebook, Friend Feed, Twitter, E-Mail
Chevrolet Volt Expects 230 mpg in City Driving
How did GM arrive at 230 mpg for the 2011 Chevrolet Volt?
Measuring and Reporting Fuel Economy of Plug-In Hybrid Electric Vehicles
Comments
Something had to done, but the whole MPGe thing rubs me wrong. In fairness to the various carmakers, they are just following the EPA's formula. The Honda Clarity is rated at 68 MPGe, but I don't wanna get started on an anti-hydrogen rant.
IMHO, Dr. David MacKay has done a superb job laying out the case for using the measure of kWh/100 km. Although this ratio is upside down from MPG that we know and love in that smaller numbers are better because it means LESS energy consumed.
This could easily be modified to kWh/100 miles, and in fact this was used for the Toyota RAV4-EV and perhaps other EVs of 1990s to early 2000s CARB fame.
David J.C. MacKay. Sustainable Energy - without the hot air.
UIT Cambridge, 2008. ISBN 978-0-9544529-3-3.
Available free online from www dot withouthotair dot com
tinyurl dot com slash n5fpbu
kwh/100 miles is a good unit of measure to compare between electric vehicles. In EV afficianado circles this sort of figure is widely used (though usually Wh/mile instead of kWh/100 miles). But most people (99.999% or more) don't grok that kinda measurement and we have 100+ years of societal experience with miles per gallon. For the time being we'll just have to live with equivalencies even though it's a bit of a crock. Further electrons don't come in gallons nor does gasoline come in coulombs so there is a need for a comparison metric of some kind. Hopefully we'll have a better time weaning people off MPG in the future than we had with enacting a conversion to the metric system.
OK.....I call BS! There is something very questionable at the way GM came to this magic number that they are blasting out to the media before they can actually prove it. Just a few months ago, it was just 40 miles per charge......so how in h*ll can it manage 230 mpg? GM is notorious for being THE most slimy, crooked auto in the world....
No?....think again.... carspiracy.com
Jim, thank you for your comment however you are talking about two different measurements. Miles of range is different from miles/gallon. As I said in the article there are known conversion forumulas for kilowatt-hours to gallons of gas (33 kwh -> 1 gallon of gas) and for example with my electric bicycle it takes 0.3 kilowatt hours to travel 10 miles. I once calculated that out to 1120 miles/gallon equivalent fuel efficiency.
The electric car is very easy to built, and very effective.
In 1899, a Belgian built electric racing car called "La Jamais Contente" set a world record for land speed - 68 mph - designed by Camille Jénatzy.
The battery pack is very short-lived, and very, very expensive.
This is the reason why “the piston cars”, are around for more than 100 years.
Their efficiency is 25% only, and still is more effective than an Electric Car.
The Battery pack is the Achilles' heel of an Electric car.
Got something to say?
Examiner.com is looking for writers, photographers, and videographers to join the fastest growing group of local insiders. If you are interested in growing your online rep apply to be an Examiner today!