The U.S. Environmental Protection Agency has an electric car problem. Federal law requires that new cars be sold with a label that includes the vehicle’s fuel efficiency as measured in miles per gallon. Yet beginning next year, gallons will start to give way to watts, prompting the EPA to redesign their window stickers.

In an attempt to smooth the transition, the EPA has adopted a new unit called miles per gallon of gasoline-equivalent (MPGe). Basically, it is a conversion factor that measures the electricity required to run the car (usually expressed in kilowatt-hours) in another unit of energy: gallons of gasoline. An all-electric vehicle should get somewhere north of 100 MPGe, even though it will never use a drop of gas.

The new figure doesn’t clear up the apples-to-oranges problem, however. Consumers tend to use the old-fashioned MPG metric as shorthand for many things—including how green the car is and the cost of driving—that don’t jibe neatly with MPGe. For example, the carbon footprint of an electric vehicle strongly depends on local electricity sources [see “The Dirty Truth about Plug-in Hybrids,” by Michael Moyer; Scientific American, July].

With so many factors to consider, the EPA created two sticker prototypes. One throws together all the information a consumer could possibly want to know in one place. The other takes the opposite approach. It is dominated by a single letter grade—A+ through D (there are no failures here)—which encapsulates all those factors in one score. Unfortunately, this simple measure would score 88 percent of all vehicles between a B and a C. “You need sufficient resolution to allow customers who say ‘I want a minivan’ or ‘I want a midsize SUV’ to meaningfully cross-shop vehicles that are similar,” says John M. DeCicco, a senior lecturer at the University of Michigan’s School of Natural Resources and Environment. “Letter grades fail on that score.”

A closer look at that sticker reveals a more important figure: how much the car will cost to operate compared with the average vehicle. Critically, the EPA adds up five years’ worth of driving. “It takes differences that are small and that you might ignore and makes them substantial but not in a misleading way—five years is an amount of time you’re likely to spend with your car,” says Richard Larrick of Duke University’s Fuqua School of Business. Larrick and his colleagues have shown that simply scaling up numbers influences consumer choice. For example, students, offered an option of two movie rental plans, were more likely to choose an extended plan when the number of movies in the plan was tallied by the year, not the month. Similarly, the EPA stickers should have the effect of promoting vehicles that are less expensive to operate, like electric cars. Good-bye gallons, and good riddance.

This article was originally published with the title Window Shopping for Electric Cars.

9 Comments

1. 1. gmrobertson@q.com 07:31 PM 10/23/10

   Consumers don't give a rip about any units except $. Why not post units in $/mile and $/lifetime repair.

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2. 2. JamesDavis 09:39 AM 10/26/10

   Electric car's pollution factor does not depend on fossil fuel driven power plants when you can created the electricity you need to recharge your battery with a solar panel. Solar Panels, after they are built - right now, creates zero pollution. You can also convert all the fossil fuel power plants to Geothermal for about the price you can build a class 4 nuclear power plant. Geothermal creates about 1.5% pollution compared to 90% pollution of a fossil fuel power plant, including nuclear.
   
   I do not think people are so stupid that they cannot realize that an electric car, like that great looking Telsa above, that can get between 150 to 350 miles per charge is a better buy than a fossil fuel car that can get 62 miles per gallon and produce 62 tons of CO1 into the air, land, and water. A simple method would be to list fossil fuel and hybrids in MPG and electric in MPC. People in America still will not convert C degrees to F degrees or versa versa and they will not convert MPG to MPC. Stop wasting our time and get those electric cars, supercharge stations that run on solar panels, out in the market place so we can buy them and get away from fossil fuels and clean up our planet.

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3. 3. jack.123 08:43 PM 10/26/10

   62 tons of CO1 from 1 gallon of fuel?huh?

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4. 4. Astrodont in reply to gmrobertson@q.com 10:08 PM 10/26/10

   Great point.
   
   'Cost' is a better indicator of environmental impact. cost reflects real use of resources.

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5. 5. tharriss 08:20 AM 10/27/10

   True, as long as you use the "true" cost... part of the reason oil/coal is considered so cheap and so hard to beat on price by green alternatives is that they only calcualte the cost of production while ignoring the cost of use (pollution, global warming, etc).
   
   Unless we tax/cap&trade the carbon pollution in some way, then we are in effect continuing to massively subsidize "dirty" power... no wonder green tech can't compete!

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6. 6. electric38 08:09 PM 10/27/10

   Yes there are quite a few choices coming.
   
   
   http://www.pluginamerica.org/vehicles/
   

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7. 7. aglindstrom 05:51 PM 12/13/10

   What does "that don’t jibe neatly with MPGe" mean? Is it US vernacular? Call me old fashioned but I found it jarring to read an ungrammatical sentence in such an esteemed magazine.

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8. 8. AbleSmith 12:38 AM 3/9/11

   These are environment friendly vehicles, less emission and higher perfomance
   <a href="http://www.usedbikesmarket.com">BMW Motorcycles</a>

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9. 9. Angel21 04:43 AM 4/22/11

   I like car features because environment friendly cars, and good performance....
   
   [url=http://www.remarkableatvs.com]Atv tires[/url]

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