Shortly after we picked up our Mitsubishi i-MiEV electric car, I bought a Kill-A-Watt meter, so that I could measure the amount of energy that goes into charging the car’s battery. I know that I pay 11¢ per killowatt-hour so this allows me the calculate the cost of running the car. I am intentionally measuring the amount of energy that comes out of my wall socket, not the amount of energy that is used to drive the car’s motor. My measurement includes energy used to run the heater, energy lost in the charger, inefficiency in the battery, etc. It is, in other words, the actual cost to operate the car and not the theoretical energy used just for propulsion.
Here are the results, after driving the Mitsubishi i-MiEV for a little more than two weeks:
- 351.8 miles
- 118.0 killowatt-hours (kWh) @ $0.11/hour = $12.98
- 3.7¢ per mile
My technique is pretty straightforward. With the battery fully charged, I reset the trip meter to 0.0 miles. After driving the car, I fully charge the battery and read the number of killowatt-hours off of the Kill-A-Watt meter. Sometimes, I don’t have time to fully recharge the car before I need to drive it again. When that happens, I do not reset the trip meter and do not reset the Kill-A-Watt meter. I then continue charging the next evening. When that happens, I end up measuring the total miles and the total energy, even if it is more than one battery charge could have sustained.
For comparison, we get about 29 miles-per-gallon with our Fiat 500 Sport, burning premium gas. Using today’s gas prices of about $3.10 per gallon, that works out to 10.7¢ per mile.
There are two other small costs worth mentioning. Missouri requires us to buy an alternative fuel sticker for the electric vehicle. The $75 annual fee for the sticker replaces the gasoline taxes that we are not paying and supports road maintenance. The Fiat, like any internal combustion engine vehicle, has higher maintenance costs associated with the more complex engine (oil changes, tune-ups, etc.)
This Google spreadsheet has the raw data for our Mitsubishi i-MiEV mileage calculations.