EPA label examples showing MPG and MPGe for gasoline, hybrid, and fully electric vehicles. (Credit: EPA) What Does MPGe Really Mean? Like miles per gallon (MPG), the higher the MPGe the better.
A car that uses 33.7 kilowatt-hours (kWh) of electricity to travel 100 miles rates 100 MPGe. When the EPA devised MPGe in the early 2000s, the government agency calculated that 33.7 kWh of electricity was comparable to a gallon of gasoline fuel in terms of its energy content.
Most people do not need the 200-400 miles of range most EVs have on a daily basis. So, if saving money while driving around town is your biggest priority—perhaps you use a gas-powered or hybrid car for longer trips—go with the highest MPGe you can find. The EPA label includes estimated gas savings for each vehicle.
How much does electricity cost per mile?
The average cost of electricity for the last several years has been about $0.12 (vertical line). The average (dashed line) crosses the vertical line at about $0.035/mile. Compare to this graph that shows driving cost for gasoline cars:
What does MPGe mean on an electric car?
MPGe is a simple, but important measurement that prospective buyers of electric vehicles and plug-in hybrids need to understand. When shopping for any type of electric car, you'll notice a slight change on the windshield label: A little "e" has found its way next to the age-old "MPG" fuel rating.
When it comes to MPGe for electric vehicles and mpg for gasoline-powered cars, they might seem very similar. But there's a big difference between the two. The formula for MPGe can be calculated as follows: 33.7 kWh of electricity = one gallon of gas. Some cars can get 100 MPGe.
Although the regulations allow some optional approaches, the most common approach is to use a factor of 0.7 to adjust all the test parameters, including range. For example: An EV achieves 200 miles on the highway laboratory test. Real-world highway driving range → 200 x 0.7 = 140 miles to account for aggressive driving and HVAC use.