# Chevy Volt gets 93 MPG in battery-only mode. Ummm...
**URL:** https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821
**Category:** Factual Questions
**Created:** [November 24, 2010, 10:57pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821 "2010-11-24T22:57:39Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [November 24, 2010, 10:57pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/1 "2010-11-24T22:57:39Z")
From [here](http://www.freep.com/article/20101124/BUSINESS0101/101124048/1319/EPA-Volt-gets-93-m.p.g.-in-battery-only-mode):
> [@](#):
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> The Volt, according to the EPA, can achieve 93 m.p.g. in its battery-only mode
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> Read more: EPA: Volt gets 93 m.p.g. in battery-only mode
If it’s battery-only, why is it using any gas?
From that same link:
> [@](#):
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> its all-electric rival the Nissan Leaf, which the U.S. Environmental Protection Agency has rated at 99 m.p.g.
How are they determining these figures? Just pulling them out of someone’s ass?
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### Author:  [@StarsApart](https://boards.straightdope.com/u/StarsApart)
#### Post date: [November 24, 2010, 11:05pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/2 "2010-11-24T23:05:18Z")
Here’s a link from CNN that explains the MPG rating for the Leaf (actually MPGe) better: [http://money.cnn.com/2010/11/22/autos/nissan\_leaf\_fuel\_economy\_rating/index.htm](http://money.cnn.com/2010/11/22/autos/nissan_leaf_fuel_economy_rating/index.htm)
> [@](#):
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> The Nissan Leaf electric car will get the equivalent of 99 miles per gallon according to its official EPA fuel economy label rating.
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> Since the Leaf uses electricity and not gasoline for fuel, the EPA had to create an “mpg-equivalent” rating.
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### Author:  [@gazpacho](https://boards.straightdope.com/u/gazpacho)
#### Post date: [November 24, 2010, 11:14pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/3 "2010-11-24T23:14:29Z")
At least the sticker has the electricity used. In slightly smaller print. 34 kW-hrs per 100 miles for the leaf. Sadly the article doesn’t give any clues into how the EPA computes MPGequivalent.
Wiki has an article about mpge.
> **[Miles per gallon gasoline equivalent](https://en.wikipedia.org/wiki/Miles_per_gallon_gasoline_equivalent)**
>
> Miles per gallon gasoline equivalent (MPGe or MPGge) is a measure of the average distance traveled per unit of energy consumed. MPGe is used by the United States Environmental Protection Agency (EPA) to compare energy consumption of alternative fuel vehicles, plug-in electric vehicles and other advanced technology vehicles with the energy consumption of conventional internal combustion vehicles rated in miles per U.S. gallon.
> The unit of energy consumed is deemed to be 33.7 kilowatt-hours witho...
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### Author:  [@Lumpy](https://boards.straightdope.com/u/Lumpy)
#### Post date: [November 25, 2010, 12:05am UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/4 "2010-11-25T00:05:16Z")
Is the Volt one of those vehicles that uses the gas engine only to trickle-charge the drive batteries? In that case you could have a small ultra-efficient gas engine and also the mpg would benefit from regenerative braking in battery mode (at least I presume they use regenerative braking).
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### Author:  [@ChrisBooth12](https://boards.straightdope.com/u/ChrisBooth12)
#### Post date: [November 25, 2010, 3:10am UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/5 "2010-11-25T03:10:27Z")
A/C maybe? power steering? Maybe it kicks on just a little to give the battery an eaiser time
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### Author:  [@Magiver](https://boards.straightdope.com/u/Magiver)
#### Post date: [November 25, 2010, 4:02am UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/6 "2010-11-25T04:02:25Z")
It’s pretty easy to use the standard cost of electricity and gasoline and make a MPG equivalent guess.
As for the gas engine, it is used after half the total charge is depleted (which is suppose to be about 40 miles). If the charge goes down too far the gas engine is actually connected to the transmission. It’s a great design but the extra cost don’t justify the fuel savings.
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### Author:  [@RandomLetters](https://boards.straightdope.com/u/RandomLetters)
#### Post date: [November 25, 2010, 2:12pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/7 "2010-11-25T14:12:28Z")
One gallon of gas contains ~33.7 kilowatt-hours of energy; the EPA is saying the Volt can go 93 miles using 33.7 kw-hr of energy - of course that would require multiple recharges, since the Volt only has about 8 to 10ish kw-hr of available battery power installed. The Leaf can manage 99 miles on the equivalent amount of energy. In gas mode, the Volt is rated at 37 mpg.
I don’t know why the EPA came out with a combined mileage figure, since that can very drastically with ones travel patterns. Someone who does ten 40 mile trips in a Volt is going to use much less gas than someone doing a single 400 mile trip.
Also, the EPA stickers do list the electrical efficiency directly, but for some reason they chose the awkward Euro style (fuel unit) per 100 (distance unit) method of rating efficiency, rather than the (distance unit) per (fuel unit) we Americans are used too. I bet most people would be less confused by a miles per kilowatt-hour figure.
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### Author:  [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)
#### Post date: [November 25, 2010, 5:04pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/8 "2010-11-25T17:04:22Z")
The EPA number isn’t reality based, since it assumes that heat can be converted to electricity with near 100% efficiency. Department of Energy assumes about 13kwh equivalent for a gallon of gas. Of course it makes more sense if the electricity comes from hydroelectric or nuclear, instead of fossil fuel.
Here is a post by Brad Templeton discussing the number. In reality, the Prius or the Insight is more energy efficient .
[http://ideas.4brad.com/nissan-leaf-epa-rating-99mpg-sadly-lie](http://ideas.4brad.com/nissan-leaf-epa-rating-99mpg-sadly-lie)
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### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [November 26, 2010, 10:52pm UTC](https://boards.straightdope.com/t/chevy-volt-gets-93-mpg-in-battery-only-mode-ummm/561821/9 "2010-11-26T22:52:57Z")
What RandomLetters said.
> [@](#):
>
> I don’t know why the EPA came out with a combined mileage figure, since that can very drastically with ones travel patterns. Someone who does ten 40 mile trips in a Volt is going to use much less gas than someone doing a single 400 mile trip.
I don’t either. it’s totally useless 'cos of the reasons you’ve said.