You Need to Compare EV Efficiency Differently

Compare apples to apples (or kWh to kWh)

Shopping for an EV (electric vehicle) is, well, confusing especially when trying to figure out how much it'll cost to drive them around town.

There are a lot of reasons for this. First, EVs are new, and even the folks selling them at the dealer level don't know all that much about them. Plus, instead of automaker ads explaining the fundamentals of EVs using well-known actor voices, we're still being sold trucks with awesome multi-function tailgates.

The all-electric Volkswagen ID.4 on display inside a dealership.

Josh Lefkowitz / Getty Images

The Monroney sticker (the piece of paper affixed to all new vehicles that show all the features, the price, its environmental impact, and its efficiency) does give you a yearly cost to run the vehicle, but it's wrapped up in MPGe (miles per gallon equivalent), a weird calculation you'll never make in real life. But there is a better way to figure this out, and the EPA and automakers should be using it instead. The miles per kilowatt-hour measurement. 

You Don't Need Calculus

On gas cars, the Monroney sticker gives you a pretty straightforward miles-per-gallon rating. You know how much gas costs, and you can figure out how it's going to impact your bank account.

Yes, the MPGe does show that if an EV ran on gasoline, it would be more efficient than a comparable internal combustion engine (ICE) vehicle. That's cool and expected, but it places a vehicle powered by lightning in a gas world.

Here is what the EPA says about MPGe: "Think of this as being similar to MPG, but instead of presenting miles per gallon of the vehicle's fuel type, it represents the number of miles the vehicle can go using a quantity of fuel with the same energy content as a gallon of gasoline. This allows a reasonable comparison between vehicles using different fuels."

Screenshot of the Fuel Economy information on a Monroney sticker.

Explain that to a friend looking to buy an EV. They'll likely just walk away mumbling to themselves about how they didn't do so great in calculus. Thankfully, there's the amount of money you'll save on gas over five years number and the annual fuel costs.

But the real info is to the right of that in a smaller font size, right above the tiny little car with the range. The amount of energy it'll take for the vehicle to travel 100 miles per the EPA's testing. For the 2022 Chevy Bolt, it's 22-kWh per 100 miles. Now we're getting somewhere.

Breaking Old Habits

My issue with this is that it doesn't line up with our way of measuring the efficiency of a car. We've trained our brains to think in units of travel per unit of energy source, aka miles-per-gallon. Also, the way the kWh per 100 miles rating is set up, the more efficient a vehicle is, the smaller the number, which again, flies in the face of how we've trained our car-driving brains.

For example, according to the EPA efficiency ratings, the Model 3 is the most efficient vehicle in this lineup (although there's a whole EPA adjustment factor that plays into that rating).

A screenshot of electric automobile listing comparisons.

But if we take that kWh/100 miles number and drop it into the calculator by dividing 100 by the miles, we get the miles per kWh. Essentially like the miles per gallon that we've been using for years, but with electricity. 

So the quick breakdown is:

  • Hyundai Kona Electric: 3.57 miles/kWh
  • Volkswagen ID.4 First Edition: 2.85 miles/kWh
  • Tesla Model 3 Long Range AWD: 4 miles/kWh
  • Lucid Air Dream AWD: 3.7 miles/kWh

That's a bit easier to wrap our heads around. So my Kona Electric will travel 3.57 miles for every kWh of energy. We're currently experiencing about 4 miles per kWh while driving the vehicle, but that's expected as some automakers (like Porsche) are essentially taking the lower range number in their EPA ratings. 

This way of reporting efficiency also makes it much easier to determine just how much it'll cost to actually drive an EV in your area. The costs vary from region to region and when and where you charge your EV, but it's a relatively easy calculation once you figure out how much you pay per kWh at home. In fact, we have a handy EV charging guide to help you figure that out. 

"The way the kWh per 100 miles rating is set up, the more efficient a vehicle is, the smaller the number which again, flies in the face of how we've trained our car-driving brains."

The weird thing about wanting automakers and the EPA to show miles per kWh is that it actually shows your driving efficiency in miles per kWh in the dash in some cars. That's how I know that we're currently averaging about 4 miles/kWh in our Kona.

The information already is being presented to drivers. But to help us truly understand how efficient these vehicles are and help potential EV owners make informed decisions that will impact their pocketbooks, everyone needs to figure out a standard that's no longer tied to the gas-powered world. 

Hopefully, as gas-vehicle production is slowly phased out, the EPA and automakers will figure this out. But for now, when shopping for a new EV, be sure to bring a calculator to the dealership and remember to look at the little number above the tiny car to see how much you'll be spending per mile.

Want to know more about EVs? We have a whole section dedicated to electric vehicles!

Was this page helpful?