Kelley Blue Book: Your complete guide to MPGe, the electric equivalent of miles per gallon
If you’ve found yourself shopping for an electrified car you may have encountered the term MPGe.
Let’s take a deep dive into MPGe. These measurements will become much more prevalent as hybrids, plug-in hybrids, fully electric cars, and fuel cell vehicles become the new normal.
What does MPGe mean?
MPGe stands for miles per gallon equivalent. Unlike a gas car’s MPG, which can be calculated using a simple formula, such a figure is not obtainable when a battery from a hybrid, plug-in hybrid, or fully electric vehicle uses electricity as its fuel source.
That’s why the Environmental Protection Agency (EPA) came up with the unit of measurement for the electric car’s energy consumption level to compare with gas-powered vehicles.
Every window sticker at the dealership is federally mandated to show the MPGe when it’s an electrified car or MPG when it’s a gas-fueled vehicle.
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How are MPGe calculated?
When the EPA devised MPGe in the early 2000s, the government agency calculated that 33.7 kilowatt-hours (kWh) of electricity is comparable to a gallon of fuel in terms of its energy content.
True, pulling 33.7 kWh of electricity from the grid in a place dependent on coal power is not quite the same as using wind power. But such an average makes for a more reasonable comparison applicable to drivers.
For example, a car that uses 33.7 kWh of electricity to travel 100 miles rates 100 MPGe.
This is simple enough for fully electric cars that do not contain an internal combustion engine. The math gets more tricky for a PHEV such as a Chrysler Pacifica Hybrid or a Toyota
Prius Prime. These vehicles use an MPGe rating when driven on electric power only, plus conventional MPG ratings that apply when their batteries are depleted and their gas engine kicks on.
MPGe is an important way to compare how efficient an electrified car is because it is directly linked to how much it costs to charge up the vehicle and how much power the EV needs to draw from the grid to top off its battery.
To be clear, good MPGe ratings don’t necessarily mean the best electric range. Instead, a high MPGe rating shows that a car makes the best use of its electrical power.
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MPGe vs. MPG
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 like this: 33.7 kWh of electricity = 1 gallon of gas. Some cars can get 100 MPGe. However, this can be misleading if you are looking at this number for how much money you will be spending on fill-ups. It would be more accurate to look at the car’s 5-Year Cost to Own and calculate how much your home electricity bill would be.
On the flip side, MPG is the gas equivalent to electric power. This number can be significantly lower than electrified cars. A car with 35 miles per gallon is considered to be great. EVs can get 100 MPGe with ease.
The miles per gallon formula works like this: miles driven divided by gallons used = mpg. This formula is much easier to understand.
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Battery-powered electric cars with the best MPGe
Expect this list to change rapidly over the next few years as battery-powered electric vehicles become more common, more energy-efficient, and more advanced.
According to the EPA, here’s a look at some of the top cars for the 2021 model year with the best MPGe, including their estimated annual fueling (using electricity and a 15,000-mile annual estimate) cost and their estimated electric range:
Model 3 Standard Range Plus: 142 MPGe – $450 – 263 miles
2. 2021 Tesla Model 3 Long Range AWD: 134 MPGe – $500 – 353 miles
3. 2021 Hyundai
Ioniq Electric: 133 MPGe – $500 – 170 miles
4. 2021 Tesla Model Y Standard Range: 129 MPGe – $500 – 244 miles
5. (tie) 2021 Tesla Model Y Long Range AWD: 125 MPGe – $550 – 326 miles
(tie) 2021 Hyundai Kona Electric: 120 MPGe – $550 – 258 miles
6. 2021 Tesla Model S Long Range: 120 MPGe – $550 – 405 miles
7. 2021 Chevrolet Bolt EV: 118 MPGe – $550 – 259 miles
8. (tie) 2021 BMW
i3: 113 MPGe – $600 – 153 miles
8. (tie) 2021 Tesla Model 3 Performance AWD: 113 MPGe – $600 – 315 miles
What MPGe cannot offer is a price comparison since the cost of a kWh varies considerably by location. Instead, a new EV’s window sticker shows an estimated annual electric cost that can be compared with one on a new gas-fueled model.
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Such information is factored into KBB’s own Total Cost of Ownership Tool, a useful way to compare how much a vehicle will cost an average driver over five years.
This story originally ran on KBB.com.