Will Ernest Moniz's eGallon Catch On?

Energy Secretary Ernest Moniz wants electric-vehicle drivers to know how much money they save by cruising past the gas pumps, so the U.S. Department of Energy unveiled the eGallon last month—a calculation of the gasoline-equivalent cost to drive an EV.
EV sales are reportedly taking off—sales doubled in the first six months of 2013 compared to the same period in 2012, according to DOE, and sales in June were the strongest on record for the United States. But the eGallon was received scant attention from the media beyond the echoing DOE press release.
That might be because it's hard to conceive of an electric gallon, and the eGallon relies on averages that make a lot of assumptions. It assumes the gasoline-powered vehicle is a 2012 model that gets 28.2 miles per gallon, an average, while the electric price averages electricity use among 5 popular models of EVs and averages standard electricity rates over a state or the nation.
Your mileage may vary.
"We take the average distance that a gasoline-powered vehicle can drive on a gallon of gas (28.2 miles for comparable 2012 model year cars), and then calculate how much it would cost to drive the average EV that same distance. Because electricity prices are a little different state to state, our eGallon tool shows how much an eGallon costs in your state, and compares it to the cost of gasoline. As you can see, on average, fueling your car with gasoline costs roughly 3 times more than fueling with electricity," said Dan Leistikow, director of DOE's Office of Public Affairs.
Soon after the eGallon debuted, the market-intelligence firm Northeast Group argued that eGallon overestimates the EV driver's cost in many states by failing to take into account discounts offered by utilities:
"Northeast Group's benchmark found that there were 24 utilities located across 13 states offering EV tariffs. In these 13 states, the average DOE eGallon was $1.40, but the average EV tariff cost was just $0.93.
"This is a discount of 34 percent from the eGallon, which is based on standard electricity rates."
Time Magazine ignored the eGallon in a recent article on falling EV prices, but a reader mentioned it in comments, reminding other readers that it doesn't take into account other saving graces of electric vehicles: "Remember, no oil changes, no air or oil filter, no emissions inspections, no tune ups…."
One of the few mainstream media outlets that has paid attention to the eGallon, the Boston Globe, noted that without the eGallon, EV drivers might be blissfully ignorant of their costs.
"The eGallon figure underscores a point sometimes overlooked," writes Doug Struck: "the fuel for electric cars, while a lot cheaper than gasoline, is not free."
Still, as DOE points out, on average it's about a third of the cost of gasoline.
The average national cost for an eGallon is $1.18 right now, according to DOE, compared to a national average of $3.49 for a gallon of regular gasoline.