If you've bought an electrified car, you may have come across the term MPGe.
Let's take a deep dive into MPGe. These measurements will be much more common as hybrids, plug-in hybrids, all-electric cars, and fuel cell vehicles become the new normal.
What does MPGe mean?
MPGe stands for miles per gallon equivalent. In contrast to the MPG of a gas car, which can be calculated using a simple formula, such a value cannot be achieved if a battery from a hybrid, plug-in hybrid or fully electric vehicle uses electricity as a fuel source.
For this reason, the Environmental Protection Agency (EPA) developed the unit of measurement for the energy consumption of the electric car to compare with gas vehicles.
Every window sticker in the car dealership is required by the federal government to show the MPGe if it is an electrified car, or MPG if it is a gas-powered vehicle.
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How are MPGs calculated?
When the EPA developed MPGe in the early 2000s, the government agency calculated that 33.7 kilowatt hours (kWh) of electricity is equivalent to a gallon of fuel in terms of energy content.
It is true that drawing 33.7 kWh of electricity from the power grid at a location that is dependent on coal power is not quite the same as using wind power. But such an average makes a more reasonable comparison possible for drivers.
For example, a car that uses 33.7 kWh of electricity to travel 100 miles costs 100 MPGe.
This is simple enough for fully electric cars without an internal combustion engine. With a PHEV like a Chrysler Pacifica Hybrid or a Toyota, the math gets harder
Prius Prime. These vehicles use an MPGe rating when they are driven only on electric power, plus conventional MPG ratings that apply when their batteries are dead and their gas engine starts.
MPGe is an important way to compare the efficiency of an electrified car as it is directly related to the cost of charging the vehicle and the energy the electric vehicle has to take from the grid to charge its battery.
To be clear, good MPGe values don't necessarily mean the best electric range. Instead, a high MPGe value shows that a car is making optimal use of its electrical power.
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MPGe vs. MPG
When it comes to MPGs for electric vehicles and MPGs for gasoline-powered cars, they appear to be very similar. But there is a big difference between the two.
The formula for MPGe can be calculated as follows: 33.7 kWh of electricity = 1 gallon of gas. Some cars can get 100 MPGe. However, this can be misleading when you look at this number of how much money you will be spending on refueling. It would be more accurate to look at the 5 year running cost of the car and calculate what your electricity bill would be at home.
On the other hand, MPG is the gas equivalent of electrical energy. This number can be significantly lower than for electrified cars. A car at 35 miles per gallon is considered great. Electric vehicles can easily get 100 MPGe.
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 are some of the top 2021 model year cars with the best MPGe, including their estimated annual fuel cost (with electricity and an annual estimate of 15,000 miles) and 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
8th (draw) 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, as the costs for one kWh vary greatly depending on the location. Instead, the window sticker of a new electric vehicle shows the estimated annual electricity costs, which can be compared to that of a new gas-powered model.
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This information flows into KBB's own Total Cost of Ownership tool, which you can use to compare how much a vehicle costs an average driver over five years.
This story originally ran on KBB.com.