Last Update: August 28, 2015
Electricity is a far cheaper fuel than gasoline, and that’s the key attribute to the low plug-in electric vehicle ownership cost.
To understand this statement we need to know how to calculate the fuel cost, for any fuel.
The benchmark will be the fuel requirement, and its cost, to go a given distance (say, 90 miles) in each vehicle. The calculations work for any fuel, for any fuel type, for any distance and for any vehicle.
The calculations are simple:
fuel reqd = distance * fuel/mile fuel cost = fuel reqd * cost/unit
To travel 90 miles in a 30 MPG car requires 3 gallons of fuel. If that fuel costs $3 per gallon, the trip cost $9.
That works for gasoline, or diesel, but how do we calculate it for electricity? We have to first get our heads around the idea that electricity is a fuel, which it is, and that it doesn’t come by the gallon but by the kiloWatt-hour. In these equations “fuel per mile” is written as “Watt-hours per mile” and cost per unit is measured per kiloWatt.
Before going deeper into what this means, let’s go over a few averages. Agencies like the Department of Transportation or Department of Energy have gone to the trouble to calculate nationwide averages for things like electricity or gasoline cost. We can use those averages to make general statements about relative fuel cost. But we also need to compare fuel cost for actual vehicles or actual driving conditions.
Average daily driving distance: The number we kick around is that the average person drives 40 miles or less per day. For more precise data, search the Internet for the Dept. of Transportation report “Our Nations Highways”. The 2011 report has a chart saying that in 2010 the average yearly vehicle miles traveled is about 15,000 per person, which works out to about 41 miles/day. The report also discusses the variability, such as the majority of trips is short distance jaunts of less than 10 miles, but the majority of miles driven takes place during trips 50 miles or more.
Average fuel efficiency of gasoline cars: This number has risen significantly since the 1970’s, according to data published by the National Highway Traffic Safety Administration. The CAFE Standard is the standardized way to measure the average fuel economy for the entire U.S. vehicle fleet. For passenger cars, the CAFE figure as of December 2014 is 36.4 MPG, where in 1978 it was 19.9 MPG.
Average cost for gasoline: The US Energy Information Administration Short Term Energy Outlook expects the average U.S. gasoline price will be $2.43/gallon in 2015, after falling from $3.51/gallon in 2013, and rising to $2.63/gallon in 2016. As we all know, gasoline prices vary wildly across the U.S. and even from week to week. The GasBuddy.com website is an excellent source for up-to-date fuel price data. As of this writing, the national average indicated by that site is $2.76/gallon, and $3.70/gallon in California.
Average fuel efficiency of electric cars: Electricity is measured in kiloWatt-hours, not gallons. There isn’t a published national average for electric car energy efficiency, but one can scan the list of cars on fueleconomy.gov and decide that the average is 250 Watt-hours per mile, or 4 miles per kiloWatt-hour.
Average cost for electricity: What we need is the cost per kiloWatt-hour for electricity, which is reported by the Energy Information Administration Electric Power Monthly report. In March 2015, residential electricity rose to 12.35 cents per kiloWatt-hour up from 12.24 cents per kiloWatt-hour in March 2014. We also see from the report that the cost varies a lot from region to region.
Hydrogen? Fuel cell vehicles aren’t widely enough distributed, there are precisely two models distributed only through select dealerships in California. We can’t do many calculations with them. According to fueleconomy.gov, one kilogram of hydrogen is roughly equal to a gallon of gasoline. The 2014 Honda FCX Clarity gets 59 miles/kg hydrogen, and the 2015 Hyundai Tuscon FCEV gets 49 miles/kg hydrogen. If only there were a clear cost per kilogram, we could perform some calculations, but the market is way too small for that purpose.
Now we can begin to calculate some cost figures, starting with the averages.
- Gasoline 90 miles at 36.4 miles per gallon requires 2.47 gallons, and at $2.76 per gallon it costs $6.82 while in California the fuel cost is $9.14.
- Electricity 90 miles at 4 miles per kiloWatt-hour requires 22.5 kWh of electricity, and at $0.1235 per kiloWatt-hour the fuel cost is $2.78 in electricity.
Now let’s calculate this for several specific vehicles, and throw in a cost per mile figure and the EPA estimated fuel cost per year. The EPA fuel cost estimate is based on 15,000 miles of driving per year, and $3.70 per gallon for gasoline. Your fuel cost will of course vary on how much you drive, and the gasoline price in your area.
|Fuel Type||Amount of Fuel, 90 miles||Fuel Cost||Total Fuel Cost||Cost per mile||Cost per year|
|Gasoline||Average:- 2.47 gallons (36.4 miles/gallon) California||$3.70/gallon||$9.14||$0.10||N/A|
|Average:- 2.47 gallons (36.4 miles/gallon) Nationwide||$2.76/gallon||$6.82||$0.08||N/A|
|2015 Chevy Cruz 1.4L Turbo:- 3 gallons (30MPG) Nationwide||$2.76/gallon||$8.28||$0.09||$1,400|
|2015 Ford Escape FWD 1.6L:- 3.46 gallons (26MPG) Nationwide||$2.76/gallon||$9.55||$0.11||$1,600|
|2015 Ford Fusion FWD 1.5L:- 3.1 gallons (29MPG) Nationwide||$2.76/gallon||$8.57||$0.10||$1,450|
|2015 Ford Focus FWD 2L:- 2.9 gallons (31MPG) Nationwide||$2.76/gallon||$8.01||$0.09||$1,350|
|2015 Ford F150 2WD:- 4.5 gallons (20MPG) Nationwide||$2.76/gallon||$12.42||$0.14||$2,100|
|2015 Honda Accord 2.4L:- 2.9 gallons (31MPG) Nationwide||$2.76/gallon||$8.01||$0.09||$1,350|
|2015 Honda CR-V 2WD:- 3.1 gallons (29MPG) Nationwide||$2.76/gallon||$8.57||$0.10||$1,450|
|2015 MINI Cooper 3 doors Manual:- 2.73 gallons (33MPG) Nationwide||$2.76/gallon||$7.53||$0.08||$1,450|
|2015 Toyota Camry 2.5L:- 3.2 gallons (28MPG) Nationwide||$2.76/gallon||$8.88||$0.10||$1,500|
|Hybrid||2015 Ford Fusion Hybrid FWD 2L:- 2.1 gallons (42MPG) Nationwide||$2.76/gallon||$5.91||$0.07||$1,000|
|2015 Honda Accord Hybrid 2L:- 1.9 gallons (47MPG) Nationwide||$2.76/gallon||$5.29||$0.06||$900|
|2015 Hyundai Sonata Hybrid 2.4L:- 2.37 gallons (38MPG) Nationwide||$2.76/gallon||$6.54||$0.07||$1,100|
|2015 Toyota Camry Hybrid LE 2.5L:- 2.2 gallons (41MPG) Nationwide||$2.76/gallon||$6.06||$0.07||$1,000|
|2015 Toyota Prius Hybrid 1.8L:- 1.8 gallons (50MPG) Nationwide||$2.76/gallon||$4.97||$0.06||$850|
|Electricity||Average:- 22.5 kiloWatt-hours (250 Watt-hours/mile, or 4 miles/kWh)||$0.1235/kWh||$2.76||$0.03||N/A|
|Average:- 34.2 kiloWatt-hours (380 Watt-hours/mile, or less than 3 miles/kWh)||$0.1235/kWh||$4.22||$0.05||N/A|
|2015 BMW i3 BEV:- 27 kWh/100 miles, 270 Wh/mile, 24.3 kWh/90 miles||$0.1235/kWh||$3.00||$0.03||$500|
|2015 Chevy Spark EV:- 28 kWh/100 miles, 280 Wh/mile, 25.2 kWh/90 miles||$0.1235/kWh||$3.11||$0.03||$500|
|2015 Ford Focus Electric:- 32 kWh/100 miles, 320 Wh/mile, 28.8 kWh/90 miles||$0.1235/kWh||$3.56||$0.04||$600|
|2015 Kia Soul EV:- 32 kWh/100 miles, 320 Wh/mile, 28.8 kWh/90 miles||$0.1235/kWh||$3.56||$0.04||$600|
|2015 Nissan Leaf:- 30 kWh/100 miles, 300 Wh/mile, 27 kWh/90 miles||$0.1235/kWh||$3.33||$0.04||$550|
|2015 Tesla Model S 60 kWh:- 35 kWh/100 miles, 350 Wh/mile, 31.5 kWh/90 miles||$0.1235/kWh||$3.89||$0.04||$650|
|2015 Tesla Model S 85 kWh:- 38 kWh/100 miles, 380 Wh/mile, 34.2 kWh/90 miles||$0.1235/kWh||$4.22||$0.05||$700|
Slashing costs even further
The already low cost of electricity as a fuel can be slashed further.
Many areas offer special time-of-use electricity rates, where night-time electricity cost is a fraction of daytime cost. With appropriate scheduling support in the car or charging station, charging sessions can start after midnight taking advantage of cheap night-time electricity.
Another option is to install solar panels on the roof of your home. Many areas allow home solar owners to sell electricity back to the grid, offsetting electricity bills. As soon as the solar panels have paid for themselves, your cost of electricity is essentially $0 and your fuel cost is $0. A variant is to install grid energy storage units (like the Tesla Energy products) alongside the solar panels.