The Hernandez family personal fleet for the past several years has consisted of a 2002 Nissan Sentra SE-R Spec V (my little toy), and a 2004 Nissan Quest SE minivan (the family truckster). Here we will provide a look into the energy cost variance in operating these vehicles given current fuel prices. This is not an attempt to determine overall cost of ownership.
First up – the Sentra. While a compact car with a 4-cylinder engine, the SE-R Spec V version is the bad boy (if such a moniker can even be applied to a Sentra) of the lineup. 175 horsepower and 180 pounds of torque would just about keep up with a 70′s muscle car in both zero-to-sixty and 1/4 mile times, while providing better fuel economy with half the cylinders. The price paid was the necessity to feed the Sentra premium gasoline. Over the nine years of possession, we racked up a grand total of just over 31,000 miles, or roughly 3,444 miles per year. The Sentra has found a new home to make way for the LEAF.
At current gasoline prices in San Diego, premium gasoline would run around $4.20 per gallon – roughly twenty cents higher than the cost of regular gasoline. If driven moderately, the Sentra would return a combined fuel economy of roughly 24 miles per gallon. Divide $4.20 per gallon by 24 miles per gallon and the result (quotient if you’re a math geek) is $0.175 per mile in gasoline cost. Now it didn’t cost us that much to drive it over the last nine years, but if we had not sold it, that is what it would cost us to drive it today. We try to look at all vehicles based on combined fuel economy, vs. city or highway. Our thinking is this – nobody lives on the highway, but most everybody uses it. Real world – everybody drives some form of combined city/highway driving. The EPA has finally recognized this, and all new cars sold since 2008 have City, Highway and Combined ratings on the window sticker. (And no… combined is not just the average of City and Highway miles per gallon. Various efficiencies (or inefficiencies) impact the combination, so it really is best to get it from the sticker).
The Quest is a different story. With its’ 3.5 liter V-6, large mass, and rectangular shape, fuel efficiency is not its’ forte. The Quest, though, can get by with regular grade gasoline. Unfortunately, the Quest’s duties included shuttling kids to school and some commuting, along with the periodic family vacation to assist in the “keeping the family sane” department. As a result, the combined fuel economy for the Quest hovers somewhere around 19 miles per gallon (and we might be slightly favoring ourselves here). In the seven years that we have been driving the Quest, it has accumulated about 90,000 miles – or roughly 12,850 miles per year. This is likely more representative of a typical vehicle owner in Southern California than our Sentra was. Divide $4.00 per gallon by 19 miles per gallon and we have $0.21 per mile in gasoline cost.
Now let’s take a look at the energy cost of the LEAF. As we mentioned previously, we are currently charging with the supplied 120 volt electric vehicle supply equipment (EVSE) using our SDG&E domestic residential (DR) rate. We admit that we are not particularly frugal in the Hernandez household and are charged the top tier of over $0.22 per kilowatt hour. This is the rate used to charge the LEAF since we got it last Friday. We are making no attempt to be refined in our discussion here, as we do not have refined numbers. Just as well, as this small sample is more for general reference than academic use. With a 24 kilowatt hour battery pack, lets say it takes 27 kilowatt hours of juice out of the wall to recharge due to some energy loss in the process. And let’s say that we are not being particularly frugal in our attempt to drive the LEAF, so we only get 75 miles out of our battery pack. This requires a little more calculation – 27 kilowatt hours of power used at $0.22 per kilowatt hour means that it would cost $5.94 to recharge the battery from empty to full. In this instance, $5.94 would move us 75 miles down the road, so $5.94 divided by 75 miles gives us an energy cost of $0.0792 per mile.
When our second meter is installed by San Diego Gas & Electric and we are placed on the electric vehicle time-of-use rate, our charge rate will drop to roughly $0.075 per kilowatt hour, for super-off peak charging between midnight and 5:00 AM. Considering that we haven’t charged at all the last two days using the supplied 120 volt EVSE, we think we’ll be able to manage that. Using the numbers from above, the cost of energy per mile drops to $0.027 per mile. Less than three cents per mile (energy cost only) to drive the LEAF vs. twenty one cents per mile (energy cost only) to drive the Quest.
We know that these numbers are fuzzy. We live in a world that isn’t always clear. We are running some numbers that apply to our situation. Your situation is very likely different. We recommend looking at your own situation if you are considering acquiring an EV.
Are electric car batteries expensive? Yes they are. Assuming stable fuel costs for the next nine years (the period of time that we owned the Sentra, and a possible lifespan for the initial battery pack), let’s take a look at the potential cost. 12,850 miles per year for the LEAF (equivalent to past mileage in the Quest) gives us energy cost alone of (12,850 miles per year times nine years times $0.027 per mile) $3,122.55. Continuing to drive the Quest (or its equivalent) for the next nine years would cost (12,850 miles per year times nine years times $0.21 per mile) $24,286.50. Driving the LEAF provides a potential savings of over $21,000 in energy cost alone. We think that might cover the cost of the battery should we decide to keep the LEAF.