Let’s start with MPG — miles per gallon. That is the “typical” distance a vehicle can travel on one gallon of fuel. Typically a gallon of gasoline but, of course, for a diesel vehicle that would be a gallon of diesel. The EPA (Environmental Protection Agency) defines typical. For example, a vehicle may have different ratings for city driving, highway driving and a mix.
With your electric vehicle you, of course, don’t have any gasoline involved. The goal of MPGe is to offer a comparison between the efficiency of a gasoline car and an electric car. For MPGe to be useful you first need to ask how much energy is in a gallon of gasoline. That answer is 33.7 kWh. So, for example, if your EV could go one mile on 33.7kWh of electricity it would have an MPGe of one.
In the real world you will find cars using a very small fraction of that much energy — such as a few hundred watts of energy per mile. If, for example, it could travel 100 miles on 33.7 kWh of electricity in would have an MPGe of 100 — far better than any gas car out there. And that is in the typical range for EVs.
