[pgfpro]

MPGe works well as a shorthand, but it doesn't tell the whole story. Let's look at how the EPA calculates MPGe.

The agency needed some way to compare two very different power sources. Gasoline and electricity use completely different units (gallons versus kilowatt-hours) so you can't just shove them into the same formula. Then someone came up with a very clever solution: If you burned a gallon of gasoline, it would generate 115,000 British thermal units of heat. So, how much electricity would it take to generate the same amount of heat? Answer: 34 kilowatt-hours (kWh). We now have our connection. One gallon of gasoline produces the same amount of energy as 34 kWh.

With this new comparison point, the EPA can now figure out how far an electric car will travel on only 34 kWh. In the case of the Mitsubishi i, that much electricity will carry it for 126 miles. So, it's 126 miles per the equivalent of a gallon of gas. Voila! You have MPGe.
Source
Electric cars 101: What does MPGe mean, exactly? - CSMonitor.com
So your car has a rating of 179 MPGe