How MPGe Works For Electric Cars
By: Originally published in Road and Track on July 1, 2022
When you read that a new electric car gets, say, 115 MPGe, it’s easy to understand why you might be confused. After all, electricity doesn’t come in gallons, and if it’s so efficient, why wouldn’t the car go further? Some may disregard it entirely. But it’s not that tough to understand and, when you do, you’ll know why it’s important.
MPG, in that regard, is a good metric. It tells you how much energy, measured in gallons of gas, you’ll consume over a given distance. MPGe is the same, except instead of a gallon of gas it uses the electric energy equivalent, 33.7 kWh of energy, as its yardstick. So each time a car uses 33.7 kWh of energy, it is burning through the equivalent of one gallon of gas.
That number, then, is exactly what it claims to be. Given the same energy as a gallon of gas, a car that gets 115 MPGe will travel 115 miles. That number is staggering. It shows that many EVs can get nearly twice as much range on 33.7 kWh of energy as a Prius can get from the same amount. It’s even more impressive when you learn that MPGe includes all of the energy that’s lost during the charging process (typically 5–10 percent) and doesn’t make it into the vehicle’s battery pack.
So why, then, are EVs not going twice as far on a charge as a Prius gets on a tank? Because range and efficiency are not the same thing.
