In the world of gas cars we have a well-accepted metric for understanding a car's efficiency: Miles per Gallon (MPG). MPG is often used to get a general sense for how "expensive" a car will be to operate. (e.g. "35 MPG is pretty good......5 MPG is pretty bad.") It also is used to compare the efficiency of two cars. However in the world of electric cars this metric obviously doesn't make sense, as there are no "gallons of gas" in an electric car.
The Electric Vehicle industry has developed a metric they hope will be an equivalent to MPG: Miles Per Gallon Equivalent (MPGe). The thought process goes like this: One gallon of gasoline contains the same energy as 33.7 kWh of electricity. Therefore, if an electric car can travel 100 miles on 33.7 kWh of electricity, it would have an efficiency of 100 MPGe. This methodology can be used to compare the relative efficiency of two electric cars. But it doesn't help gasoline car owners get a sense of the operating costs of an electric car. Our electric car has an MPGe of 117 city and 131 highway. I don't know about you - but that data doesn't help me understand whether operating this car will be "expensive" or "cheap".
We took delivery of our electric car on Dec 8, 2021. Through Jan 31, 2022 we've driven 635 "local" miles (i.e. errands and other trips close to home). We also drove 2,911 miles over 9 days during a trip to CA and back. The following cost comparison excludes that road trip - since that was not "typical" driving for us.
Gasoline Vehicle Cost
Our electric car replaced a 2019 GMC Terrain. The Terrain typically got about 25 MPG in city driving. 635 miles would require a little over 25 gallons of fuel. At $3.34/gal - that's a fuel cost of $83.50.
Electric Vehicle Cost
We charge our car using electricity from two sources. Our preferred power source for car charging is our solar panels. If we're not able to get the power we need from solar we pay for power from our electric company - like we do when we use any other electric appliance in our house.
Driving the 635 of in-town miles required 301 kWh of electricity. 251 kWh came from the solar panels. 50 kWh were purchased from the electric utility.
The 251 kWh from solar that went into the car weren't "free". If we had returned that power to the utility (sold it to them) we would have received $15.06 of credit toward our electric bill. The 50 kWh we purchased cost us $3.50. Therefore, the energy needed to drive those 635 of in-town miles cost us $18.56. This, of course, does not include other costs of gas cars such as oil changes, etc. Including those would make the difference even more dramatic.
$83.50 for gasoline vs $18.56 for electricity - to drive 635 miles. On a per-mile basis the electric car costs us about 22% of the cost of a gasoline vehicle.
Not everyone has solar panels. So what would the energy for the 635 miles cost if all of it had been purchased from our utility? $24.57. Still - considerably less expensive than gasoline-based transportation.
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