MPG vs MPGe Explained
Last updated July 24, 2026
Comparing a gas car's MPG to an EV's MPGe can feel like comparing two different languages. Here is what each one actually measures, and how to translate both into a number you can budget with.
What MPG measures
MPG stands for miles per gallon, a straightforward measure of how far a vehicle travels on one gallon of gasoline or diesel actually burned. Because liquid fuel has a fixed, well understood energy content, MPG has worked as a simple, direct way to compare gasoline and diesel vehicles against each other for decades.
What MPGe measures
Electric vehicles do not burn fuel, so there is no gallon to count. EPA created MPGe, miles per gallon equivalent, to express an EV's energy efficiency in a unit that gas car shoppers already understand.
The conversion relies on a fixed EPA constant: one gallon of gasoline is defined as equivalent to 33.7 kilowatt hours of electricity, based on the energy content of a gallon of gasoline. An EV's MPGe rating is simply how many miles it travels per 33.7 kilowatt hours of electricity consumed.
Why MPGe numbers look so high
Electric motors convert stored energy into motion far more efficiently than an internal combustion engine, which loses most of its energy as heat rather than forward motion. That fundamental efficiency advantage is why an EV's MPGe rating commonly lands somewhere around 100 to 130, several times higher than even an efficient gasoline car's MPG rating in the 30s or 40s, despite the vehicles often being similar in size and weight. The high number reflects genuinely superior energy efficiency, not a scoring quirk.
Comparing cost, not just efficiency
MPGe measures energy efficiency, not what you will actually pay. Electricity and gasoline prices vary widely by region and change independently of each other, so two vehicles with very different MPG and MPGe ratings can end up costing a similar amount to drive, or a very different amount, depending on local prices.
The most useful way to compare a gas vehicle to an EV for budgeting is cost per mile using your own local fuel and electricity prices, which is exactly what a side by side calculation on this site is built to show.
The real world gap works differently too
Just like MPG, an EV's real world MPGe can diverge from its EPA rating, but the causes are different from a gas car. Cold weather and sustained highway speed are the two biggest factors, both covered in more detail in our guide to how EPA ratings are measured.
Turning MPGe into a cost you can budget with
Working through the actual conversion makes the relationship concrete. Take an EV rated at 100 MPGe combined: dividing EPA's 33.7 kWh gasoline equivalence constant by 100 gives 0.337 kWh per mile, or 33.7 kWh per 100 miles. At a residential electricity price of 19 cents per kWh, that works out to about 6.4 cents per mile, versus roughly 13 cents per mile for a 30 MPG gas car at 4 dollars a gallon. The same math scales to any MPGe rating and any local electricity price, which is exactly what a cost-per-mile EV versus gas comparator automates for you.
Two things commonly shift that result in practice: charging location and time of use pricing. Charging at home, often on a discounted overnight utility rate, is normally where the bulk of an EV's cost advantage comes from. Relying mainly on public DC fast chargers, which frequently price electricity at two to three times a typical home rate, narrows the gap significantly and can occasionally erase it against a genuinely efficient gas or hybrid vehicle.
How MPGe applies to plug-in hybrids
A plug-in hybrid is the one vehicle type that gets both ratings on the same window sticker, because it genuinely operates both ways. Its MPGe figure describes efficiency while running on battery power alone, typically for the first 20 to 50 miles depending on battery size, while its separate MPG figure describes efficiency once the battery is depleted and the gasoline engine takes over as the primary power source. A driver whose daily trips stay within the electric-only range will see results much closer to the MPGe figure, while a driver who regularly exceeds it will see something closer to the gasoline MPG figure instead.
Frequently asked questions
Not automatically. MPGe measures energy efficiency at the vehicle, not how the electricity was generated. An EV charged from a cleaner regional grid will have a smaller environmental footprint than one charged where electricity comes mostly from coal, even if the MPGe rating is identical.
You can compare the two ratings as efficiency figures, but for a cost comparison you need to convert both to cost per mile using local gasoline and electricity prices, since the two ratings are not measured in the same currency of energy cost.
A plug in hybrid typically gets both a combined MPGe rating for electric only driving and a separate MPG rating for once the battery is depleted and the gasoline engine takes over, since it can operate in either mode.
That figure is the actual energy content of one gallon of gasoline, a physical constant rather than an arbitrary conversion factor, which is what makes MPGe a genuine apples to apples efficiency comparison rather than a marketing number.
Yes. MPGe applies to any vehicle that runs on a fuel not measured in gallons, which includes hydrogen fuel cell vehicles and compressed natural gas vehicles alongside battery electric vehicles, all converted back to the same gasoline-equivalent energy basis for comparison.
No, they measure different things. Battery capacity determines how far a charge lasts, essentially the EV equivalent of tank size, while MPGe measures energy efficiency, how far the vehicle travels per unit of energy consumed regardless of how large the battery is. A small, light EV with a modest battery can post a higher MPGe than a larger, heavier one with a bigger battery, the same way a compact gas car often beats a larger sedan on MPG despite having a smaller tank.