Posted on August 04, 2019 by Charles Morris
For some buyers, the savings on fuel and maintenance costs is one of the motivations for buying an electric vehicle. Those who actually own one know that the main advantage of going electric is the superior driving experience - however, the savings certainly offset the higher purchase price of an EV, and in some cases may result in the total cost of ownership being lower than that of a comparable legacy vehicle.
Above: Model 3 charging at Tesla's Design Center in Hawthorne, CA (Instagram: @fromwhereicharge)
But how to estimate the potential savings? It’s a complex calculation that will be different for every driver - gas and electricity prices vary widely depending on where you live, and of course how you use your vehicle is another major factor. Cameron, the producer of The Tech of Tech YouTube channel, has prepared a handy Electricity vs. Gas/Diesel Savings Calculator that you can use to calculate the potential savings in any desired scenario.
First you need to figure out how many miles you drive per month, on average. Unless you have a very rigid schedule (for example, commuting five days per week, and never using your car for any other trips), your estimate of the number of miles you drive is not likely to be very accurate. Most people vastly overestimate the distances they drive, which is part of the reason range anxiety is such a prevalent problem. Therefore, I recommend using hard numbers: dig out the receipt from your last oil change, or your vehicle title, and note the odometer reading listed there, then take a current odometer reading, and do the math to calculate how many miles per month you’ve actually been driving.
The next step is to find the efficiency rating for your EV (or for ones you’re thinking of buying). Figures for current EVs can be found at InsideEVs, and data for previous years’ models can be found at www.fueleconomy.gov. As is the case with gas cars, there are separate city, highway and combined efficiency figures, so you may choose to fudge the number a little to make it fit your typical driving conditions. If you already own an EV, you should be able to find the actual efficiency number in your data logs. This would be the best number to use (the EPA says my 2015 LEAF should get 3.33 miles per kWh, but the LEAF itself tells me it gets 4.2).
Different sources use different ratios to express efficiency. My LEAF (and some other non-Tesla EVs) expresses efficiency in miles per kWh, whereas Tesla expresses it in watt-hours per mile. Cameron's calculator includes a handy conversion table for those who don't relish delving into the algebra. (There’s a lively discussion on the relative merits of the two different ratios on the Tesla Forum.)
Above: Filling up at a gas station vs. an electric bill increase after buying an EV (YouTube: The Tech of Tech)
Note that all three versions of Model 3 are some of the most efficient EVs available, topped only by the new Hyundai Ioniq. The larger and heavier Models S and X are less efficient, but still blow away the Jaguar I-Pace and Audi e-tron, two new crossover EVs that are often described as Tesla competitors.
Next, enter your cost for electricity in dollars per kWh, which you should be able to find on your electric bill. Cameron is one of the lucky souls whose local utility offers time-of-use (TOU) billing, which greatly adds to the savings (in Florida, where I live, we pay full freight).
We don't want to overstate the savings from going electric (perish the thought), so we need to account for the efficiency of your home charger - that is, the amount of energy that's lost to heat in the charging process. There’s a lively discussion of charging efficiency on the Tesla forum. Contributors seem to agree that the efficiency of Tesla chargers runs roughly around 80%.
Next, enter the fuel efficiency in mpg for the legacy vehicle that you want to use as a comparison. This could be your current vehicle, but it’s probably more realistic to select one that represents what you would buy if you didn’t buy an EV.
Finally, enter the typical cost of gas/diesel per gallon in your local area (if you’re not one of those who keeps track of gas prices, check GasBuddy for the best prices in your area). Note that regions with high electricity prices also tend to have high gas prices, so while both vary widely, the amount of savings is substantial just about everywhere. Cameron plugged several sets of figures into his calculator, and says he didn’t find anywhere in the US where you wouldn’t save money by driving electric.
So, how much can you save? Well, maybe a little, maybe a lot. Those who put a lot of miles on their cars stand to save the most (which is why taxi fleets around the world are steadily trading in their Crown Vics for Teslas). Cameron is a poster child for savings - he puts a hefty 1,800 miles per month on his Model 3, his utility offers a TOU rate, and his second car is a gas hog that gets a pathetic 12 mpg. He figures he’s saving over $120 per month by driving his Tesla Model 3 compared to driving a competing ICE sports sedan. I’m at the other end of the scale - I drive a modest 520 miles per month, my electric rate is 11.57 cents per kWh (just under the US average), and my second car is an abstemious Prius. But even with all of these factors eroding my savings, I’m still coming out ahead by almost $50 per month. So when your EV-curious friends ask if driving an EV saves money, the short answer is absolutely, in almost any conceivable use case.
Above: Model 3 at night (Instagram: @fromwhereicharge)
As you can probably see by now, calculating real or potential savings is an inexact process - gas prices change, and vehicles don’t always get exactly the efficiency figures calculated by the EPA (Cameron tells us that real-world efficiency figures for Teslas are usually better). Furthermore, you may find that your use case changes once you buy an EV. For example, since my wife and I made the LEAF our second car, we tend to use it instead of the Prius whenever possible, not only to maximize the savings, but because it’s more fun to drive - if you buy a Tesla, you’ll almost certainly have a similar experience.
Written by: Charles Morris