EVs Don't Cost Much to Run

But the Math is Tricky

Inside this Article

Author with vehicle
The author with his all-electric 2012 Nissan Leaf.
Plug in the vehicle to recharge
Refueling an electric car is easy—just plug it in to recharge the batteries.
Onboard tools
Using onboard tools helps Nissan Leaf drivers plan their cars’ refueling for times when electricity rates are cheaper.
The dashboard also displays the vehicle’s energy use.
Electric vehicle service equipment
The hardware on the wall, known as electric vehicle service equipment (EVSE) is a networked supply of 240 V electricity. This EVSE—Blink, provided by The EV Project, monitors and transmits charging patterns to a central database. The Blink charger also has a small monitor that allows users to track charging.
PV Array
A 5.89 kW batteryless grid-tied system helps offset utility electricity use for the home and car-charging. This subsystem of nine modules sits on the carport roof.
PV System used to offset vehicle charging
In many locations, a 2.5 to 3.5 kW batteryless grid-tied PV system can provide sufficient energy to offset common EV driving patterns.
The author in his vehicle
Even if exact numbers are hard to pinpoint, the economics of driving an EV are compelling—less than half of what a 40 mpg gas car costs to fuel. An electric car’s environmental benefits and fast, smooth acceleration are icing on the cake.
Author with vehicle
Plug in the vehicle to recharge
Onboard tools
Electric vehicle service equipment
PV Array
PV System used to offset vehicle charging
The author in his vehicle

The low cost of fueling an electric vehicle is often cited as its chief benefit. Plug-in car advocates say that battery-powered cars cost about $0.02 per mile to run—that’s roughly one-sixth the cost of powering a moderately fuel-efficient gasoline-powered car. But just how accurate is that number?

Electric car drivers don’t typically monitor their EV’s electricity use—their home and car’s energy consumption often get lumped together. Whether metered separately or not, the price of electricity can vary depending on the time of day, time of year, and the overall monthly electricity consumption, making quantifying EV electricity use even more complicated. All details, such as your local rates and type of electric car, could shift the numbers one way or the other.

Two Typical Months

It would be a fool’s errand to try nailing down a single price for all EV drivers across the country—or even in one town. Instead, I’ll focus on what I paid during two specific months in 2012—February and May. The “test case” is my all-electric 2012 Nissan Leaf plugged into Pacific Gas and Electric’s (PG&E) grid in the San Francisco Bay Area. A 3.3 kW grid-tied, net-metered PV system offsets some of my household’s electricity and provides some charging electricity for the Leaf.

PG&E offers special EV residential electricity rates, and with its seasonal and usage tiers, the price for 1 kWh of electricity (in the high season—summer) ranges from $0.037 from midnight to 7 a.m. to as much as $0.54 per kWh—almost 15 times as much—during a summer afternoon.

I determined my EV’s charging usage through reports provided by Blink, the charging network that tracks how much electricity flows through my home charger (which they document as part of The EV Project, supported by the U.S. Department of Energy­—see sidebar).

In February, I used 385 kWh to recharge the Leaf—out of the total of 954 kWh I purchased from PG&E. In May, I bought a lot less electricity (461 kWh), since my PV system was generating more electricity, but the EV still used almost as much juice—342 kWh.

Figuring It Out

Are PG&E’s current EV electricity rates confusing? Extremely. If I begin a four-hour charge at 10 p.m. in the winter, the first two hours of charging cost $0.09 per kWh. But at midnight, the price is cut in half to about $0.045 per kWh. Let’s assume that charging energy use is steady for the entire four hours, even though the energy flows a little faster during the first few hours and tapers off as the battery fills up. And for simplicity, let’s say that I charge exactly the same amount every day of the month, since averaging helps calculate the impact of a tiered pricing structure.

In February, for the first 10 days of usage, I paid $0.046 per kWh. On the eleventh day, I reached the baseline for Tier 1, which then pushed my rate up 40%, to $0.0645. By May 19, my rate for daytime peak electricity jumped to a whopping $0.54 per kWh. Utilities rightly discourage EV charging and other energy use during the day in the summer, when most air conditioners are running.

In February 2012, I used 385.12 kWh to recharge my Leaf. Of those, 243.31 kWh were during off-peak hours, costing $28.93. The other 142 kWh were during partial-peak hours—weekday mornings. For the first 49 kWh of those partial-peak 142 kWh, I spent $4.82. But because of tiered price structure, the final 44 kWh of the month cost $14.83—more than three times the cost for fewer kWh. The total for partial-peak charging was $30.65. The combined off-peak and partial-peak for February’s EV electricity bill was $59.58. That’s an average rate (across all times and tiers) of $0.1547 per kWh.

Comparing to a Gasoline Car

According to my Leaf’s onboard stats, I am a moderately efficient driver at 3.3 miles per kWh. (EV drivers who are light on acceleration and good with coasting can get 4+ miles per kWh.) But for me, those 385 kWh provided 1,270 miles of travel.

If I had been driving a 40 mpg gasoline-powered car, the cost for those 1,270 miles would have been $127, at $4 per gallon. So the cost savings in the electric car in February was $67.41. If all of my charging would have been during off-peak hours, I could have added another $14 to that savings.

Comments (10)

Jim and Elaine Stack's picture

Rob, Thanks for the warning. I thought Chevy would be much better than that. Our LEAF and FOCUS have been perfect from day one. The few we talked with that had problems were all given loaners and the problems fixed quickly.
Sorry about you experience. Let us know if they get their act together. Maybe a Tesla Gen III in 2015 will put them all on alert and may them shape up or miss out on service.

Robert Pollock_2's picture

Jim & Elaine Stack; I just read your comments and you sound just like I did a few weeks/months ago. The Spark EV I leased 9 days ago has been back at the dealer for 6 of those 9 days. The Odometer reads 207 miles, about 40 to 60 of which I, or my wife put on the car until it was dead. It can't be charged and they don't know why. This is the second time they've had it for days, and always gave it to me with 3/4 charge showing, which in itself makes you wonder, why not full?
The manual says to keep it full, but you can't. It shows about 58 miles now, so by end of day tomorrow I'll be calling I-star again, to have it taken back to the shop. This is not funny, but Chev will not get me another car or tear up the lease on this one. Rarely would I say this about someone because I not qualified to make the judgement, but he sales people at Diamond Hills Auto Group Chevrolet are not only ignorant regarding Electric Cars, (they told me about the free oil changes) they're just plain stupid people that are through learning. Ask any one of them what OHM's law is? I learned that in school, age 14 or so. They all missed that part, and the rest.
This is funny; When the battery is dead, there is enough power to call Onstar, but during the message the car cuts off the connection to save power. Take you cell.

Robert Pollock_2's picture

Living in Palm Springs, sunshine and Electric cars seem as natural as the desert and mountains. I researched EVs for six months then decided on a Spark EV, but the 2LS with the DC Fast Charge option.
That lead me into the sleazy morass of 'business' thugs called Chevrolet. The long version, we were going to court because they lied to me about the charging options. They lied because they didn't know what it was, for one thing, and because they tell you anything you want to hear, for another.
I decided my credit rating was worth more than their car, so I capitulated and now have an obsolete EV. I will hate, and I mean hate, Chevrolet for a long time. I want to tell people about EVs and to stay away from Chevrolet, which of course is, General Motors. They sell sophisticated 21st century electric cars, but are still controlled by 20th century bait and switch and enforcer, thug like pressure tactics.

Jim and Elaine Stack's picture

All electric vehicle and even plugin hybrids and hybrids have a 8 year 100K mile warranty. So we can know that batteries will last that or twice as long.

The EV's with liquid cooling think they might last the life of the vehicle! We will see and just like solar panels the warranties will increase as they prove to last longer in the real world..

Jeff Bohnert's picture

Ok, but what about battery life, and replacement cost?
My laptop battery does well in it's first year but by the start of the 3rd year it is only at about half the capacity. Heck 1 year in on my iPhone and it's showing serious signs of storage issues.
I will say though I have a Li-ion powered 40v lawn trimmer that I quite like because I don't have to mess around with mixing fuel, changing a carb, pull starting, or listening to the noise all advantages I would be happy with in an electric car.

Robert Winfield_2's picture

for a useful graphic, the US govt collects weekly fuel prices
They only have 1991 forward. If you graph regular gas prices, it is nearly a flat line from 1950-about 2000. If you graph from about 2001 and extend to 2021, you can eyeball a regression line showing that in about 3 years regular gas will be over $6.00 and in about 5-5.5 years be over $7.00/gallon with NO oil shocks. If you graph worldwide production of oil, you will notice the graph is getting a flat top, no matter what is done, more cannot be pumped because there is NOT more to be pumped, hence rising prices

Robert Winfield_2's picture

There are a few other positives of EV's (and PV). The ubiquity of literally billions of 120v outlets in the US that can be used to charge up.
During Superstorm Sandy, there were very long lines to get gasoline at the very few operable fossil fuel stations.
During the Derecho on the East Coast last summer, power was also knocked out, for a shorter time.
In both instances, members of EVADC managed power, one tapping off the 12v in his PHEV Prius with a 1kW inverter to have power for the refrigerator and a few lights with the PRius in ready mode to fill the 12v battery as needed from the traction battery
Several other members tapping off their Leaf's 12v with a pure sine Xantrex 1kW inverter to also power the refrigerator and a few lights. If necessary after about 3 days, the Leaf could have been driven to a 120v plug or 220v plug and the traction battery recharged.
Both instances use the main traction battery to keep the 12v battery charged. It really works

I have a graphic but cannot paste it here


Michael Welch's picture

Hi Robert. Great info, and really good points. Specially appreciated hearing that folks have become creative with their EVs in the wake of those disaster grid failings.

rumpole's picture

Your 4.2 cents/mile is in line with my 3.5 cents/mile for my Leaf. My utility in Maryland, PEPCO, doesn't use TOU rates, so the calculation is much easier. I get the kWh data from the CARWINGS web site, which conveniently records all of my driving data, including energy usage. I spend about $50.00 per month in electricity for the car.

The comparison to an ICE vehicle should probably be made to the car the Leaf replaces, a 1998 Saturn SL2, in my case. I managed 30 mpg out of it, which worked out to 12 cents/mile. So, I have a cost reduction of a factor of about 3.5 .

As the Stacks point out, the real payoff is in what I call "cutting the nozzle". It is so liberating not to be dependent on whatever the asking price is at the pump.

Jim and Elaine Stack's picture

the real payoff is never having to stop and fuel up, just plug in while you sleep Off Peak at night. Clean, efficient the only way to travel.
Unless you can travel at the speed of light for fractions of a cent on telecommunications and fiber optics. Being there takes time and money, calling takes seconds. Video conference takes seconds.

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