The True cost of Powering an Electric Car

The True Cost of Powering an Electric Car, either at charging stations or in your home, might not be what you imagine when considering buying one.

What if a gallon of gasoline cost $2 at night, was free between noon and one o’clock, and climbed up to $8 during rush hour? Welcome to the world of electric cars. If you buy one, the cost of a fill-up will largely depend on when and where you recharge it, not to mention the rates your utility company offers.

In the United States, the cost of electricity varies far more than the cost of gasoline. One kilowatt-hour averages 8.6 cents in the State of Washington, all the way up to 37 cents in Hawaii. (A kilowatt-hour [kWh] is the amount of electrical energy consumed when 1,000 watts are used for one hour.) Depending on the availability of public charging, you might be able to recharge your electric vehicle (EV) for free during a lunch stop at the mall. But if the EV is going to be filled up at home, your rate could be much higher than the national average of 12 cents that the EPA uses on its fuel economy label for EVs.

Because of the variety of utility rates in the U.S., a 2013 Nissan Leaf that’s a bargain to drive at average electricity rates in Washington (approximately $25 for 1,000 miles) is a lot more in Hawaii. That same 1,000 miles would cost about $107. A conventional car would have to be getting 140 mpg to make that trip for the same money in Washington, while in Hawaii, a 38.5-mpg gasoline vehicle would do the trick.

For consumers primarily interested in driving an EV to save money, it’s critical to know actual electricity rates (and the current cost of gasoline, for comparison purposes) instead of relying on national averages.

To figure out the cost of fueling an EV, start with the electric car’s energy consumption rate, which is expressed as kWh per 100 miles (kWh/100m). This figure is listed on the EPA’s EV fuel economy label and the government’s fueleconomy.gov Web site. The next figure is your home electricity rate, assuming that home is your primary charging site. Multiply the kWh/100m figure by the electric rate to get the cost per 100 miles.
For instance, the 2013 Leaf’s kWh/100m figure is 29. If electricity is 12 cents per kWh — the national average — it would cost $3.48 to go 100 miles.

The cost of electricity is based on the rates set by utility companies, time of use and level of use. The more electricity you use, the more money you pay for it. Consumers generally pay more per kWh for electricity that’s used at peak hours. Unless EV buyers do some planning, they could find themselves paying rates much higher than the national average of 12 cents per kWh.

As the EPA mileage sticker for EVs reminds us, your results may vary, depending not only on the efficiency of the EV you’re driving but also where and when you’re charging it.