"The energy contained in 1 gallon of gas is equivalent to 33.7 kWh (kilowatt hours) of electricity. So for example, if an electric vehicle can travel 100 miles on 33.7 kWh of electricity, it would be rated with an MPG equivalency of 100 MPGe."

https://www.merchantsfleet.com/future-of-fleet/mpge-explaine...