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You Need to Compare EV Efficiency Differently

Compare apples to apples (or kWh to kWh)

By Roberto Baldwin Roberto Baldwin Brooks College Academy of Art University Roberto Baldwin is a freelance journalist that has covered automobiles with a focus on EVs and mobility for a range of publications. lifewire's editorial guidelines Updated on October 1, 2021 04:04PM EDT Fact checked by Rich Scherr Fact checked by Rich Scherr University of Maryland Baltimore County Rich Scherr is a seasoned technology and financial journalist who spent nearly two decades as the editor of Potomac and Bay Area Tech Wire. lifewire's fact checking process Tweet Share Email Tweet Share Email Smart & Connected Life Mobile Phones Internet & Security Computers & Tablets Smart Life Home Theater & Entertainment Software & Apps Social Media Streaming Gaming 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. 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." 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).
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/kWhVolkswagen ID.4 First Edition: 2.85 miles/kWhTesla Model 3 Long Range AWD: 4 miles/kWhLucid 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? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit More from Lifewire What Does an EV Battery’s Miles per KWh Number Mean? EV Ranges Explained: EPA, WLTP, and NEDC How Much Does It Cost to Charge an EV? Can EV Batteries be Replaced or Upgraded? How ‘Green’ are Electric Vehicles, Really? 5 Reasons People Don't Buy EVs 43 Most Common EV Questions Answered How to Read an EPA Fuel Economy Sticker for an EV Apple Car: News and Expected Price, Release Date, Specs; and More Rumors EVs and Electric Bills: Myth vs. Fact Is an Electric Vehicle Right for Me? Is It Better to Charge My EV at Home or at a Public Charger? What’s the Shift to Electric Vehicles All About? How Much Range You Need in Your EV Level 1 vs. Level 2 vs. Level 3 Charging Explained 8 Things to Consider Before Buying a Used EV Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. Cookies Settings Accept All Cookies