Here's what I found online about that ..
The Nissan Leaf's EPA window sticker touts "99 miles per gallon" in large font. Since the Leaf is a fully electric car and does not burn gasoline, this might seem odd. But look more closely and you'll see the Leaf's "99" is actually an mpg-equivalent (mpg-e) figure, which is the Environmental Protection Agency's (EPA) way of converting the power used by an electric vehicle (EV) into a term familiar to most Americans. This 99 mpg-e number is ultimately more useful for comparing energy consumption than fuel costs, but we'll decode the EPA's electric-car mpg stats and explain what it means to you and your pocketbook.
Kilowatt-Hours to MPG-Equivalent
So how does the EPA get from 34 kWh/100m to 99 mpg-e? To create the mpg equivalent, the EPA uses an established energy standard of 115,000 BTUs (British thermal units) per gallon of gasoline. Grossly oversimplified: If you ignited 1 U.S. gallon of unleaded gasoline, it would generate that much heat. To create the same amount of heat, you would need 33.7 kilowatt-hours of electricity.
So if the Nissan Leaf could travel 100 miles on 33.7 kWh of electricity (the energy equivalent of 1 gallon of gasoline), it would receive an mpg equivalency of 100 mpg-e. Since the Nissan Leaf requires slightly more than the 33.7 kWh gallon-of-gas equivalent to travel 100 miles (in this case, 34 kWh), it received an mpg equivalency rating of 99 mpg-e. What does all this have to do with fuel economy? Not much.
The mpg-e rating is really only useful for comparing the relative energy consumption of gasoline (or hybrid) cars with that of electric cars. The Leaf uses the energy equivalent of 1 gallon of gasoline for each 99 miles of travel, compared to a hybrid Prius, which would use roughly 2 gallons of gasoline for every 99 miles it travels. Far more pertinent for electric car owners focused on cost is the kilowatt-hours-per-100-miles rating (kWh/100m), which shows you how efficient the vehicle is at converting electricity into miles traveled. The kWh/100m rating is the new EV mpg, and from a pocketbook standpoint, lower is better.
You're welcome. :)
Yes. They love to twist facts. Note that GM closed the factory that made batteries for its Volt because nobody wants to buy it.