EPA Produces MPG-e Ratings for Plug-in Hybrids
November 29th, 2010 by 
It looks like the debate on fuel economy for plug-in hybrids rages on unabated. General Motors just announced that its Chevy Volt plug-in hybrid car will carry a better efficiency rating that the Toyota Prius (long been recognized as the industry leader in the category). The fact that this is like comparing apples with trombones doesn’t seem to be of any major concern to GM, the EPA, or anyone else.
According to Sharon Terlep, writing for the Wall Street Journal:
The Environmental Protection Agency (EPA) handed down three different mileage ratings for the Volt, based on how it is driven. This marks the federal agency’s first attempt to hand down a miles per gallon equivalent or MPGe rating. The Volt sticker prominently displays 93 as the miles-per-gallon equivalent when the car is driving on the battery alone; 37 miles-per-gallon is the figure when the gas engine is delivering power to the electric drive system. In smaller letters, 60 miles per gallon is listed as the comparable to other compact cars.
93 miles per gallon – when driven in a mode that doesn’t use any gasoline? Doesn’t this require clarification?
If I were writing the charter for the EPA, it would include the notion of elucidating and to trying help consumers wrap their wits around a new area of technology — not further confusing them. Maybe that’s why I didn’t get the job.
photo: drpeppermuseum.
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Tags:  Chevy Volt electric drive system epa fuel economy miles per gallon MPGe plug-in hybrid | [ Permalink ] |
It is probably MORE confusing to consumers to explain how the MPGe figure is calculated considering the complexity of the nation’s electricity grid. I figure that the 93 MPGe number uses publicly available e-grid information from the EPA, but it must use the national average that is a weighted product of regional figures. Different regions have different carbon emissions factors… so the MPGe will be drastically different depending on whether you are plugging in at night in Washington State or Kentucky.