Only 3 cents a mile

 

How much does it cost to drive a gasoline powered car a distance of one mile?  The price varies by a number of different factors, including the price of gasoline, the cost of an oil change, the cost of an emissions test, and the cost of a minor tune-up.  The fuel efficiency of the engine also figures in significantly.  A typical small sedan might average about 25 miles per gallon.  Gasoline fluctuates between $3.50 a gallon in the winter and $4.50 a gallon in the summer, so I’ll pick an average price of $4.00 a gallon.  I can get a smog check every two years for $60, an oil change every 5,000 miles for $80, and a minor tune-up every 15,000 miles for $150.  (There are other service items too, but these will make my point.)  The cost to drive this small sedan 30,000 miles over three years is:

expense	times	cost
Gasoline	1200	$4,800
smog check	1.5	$90
oil change	6	$480
minor tune-up	2	$300

That amounts to $0.19 a mile.  (A SUV that gets 16 MPG costs $0.28 a mile.)

The cost to drive an electric car is basically a function of the cost of electricity and the range per kilowatt-hour.  Assuming electricity can be bought for $0.145 per kWh, and a typical range of 4 miles per kWh (according to the EPA), then the cost per mile is (simply) $0.036.  My car is fast approaching 30,000 miles on the odometer, which means that I have saved approximately $4,600 over the cost of driving a small gasoline powered sedan.  Of course, I squandered my savings on additional solar panels, which dropped my electric bill to about $85 a year to drive 10,000 miles, saving me another $825 over the same three years.  (And, the solar panels should remain in service for 20+ years.)  So, when figuring the total cost of a gasoline powered car, you need to think beyond the sticker price and look at the additional costs of ownership.  Even factoring in a new battery after 10 years of driving I still come out thousands of dollars ahead.

The carpool lane

One of the big incentives for most electric vehicle customers in the San Francisco Bay Area is the access to the diamond/carpool lane.  For commuters that have inflexible work hours, driving in the carpool lane can cut ten minutes or more from your trip.  Because of the hours I tend to drive, the carpool lane is seldom an option for me.  Along my route to work, the carpool lane is restricted only during the morning and afternoon peak hours, and I tend to commute just after each of these restricted periods.  So, most of the time, the carpool lane is not a viable option.  Of course, the carpool lane is not without its costs either.

 

Like any car, an electric car uses the least amount of energy when a steady speed is maintained.  Although stops can recapture up to one-third of the energy used to accelerate, it cannot recapture all of the energy, nor do you recapture the steady-state energy.  The trouble with driving the carpool lanes is the unpredictability of the flow of traffic.  At any moment, a car ahead of you may need to slow in order to change lanes, or another slower car can pull in front of you from an adjacent lane.  Finally, getting into the carpool lane often requires harder acceleration than simply pulling onto the freeway (if you want to avoid a rear collision).  So, on those few trips I take when the carpool lane is available, I tend to evaluate the flow of traffic outside the carpool land and decide whether traffic is moving steadily or stopping and starting.  I will stay in a steadily moving lane as long as the speed is at least 30 MPH and elect to use the carpool lane when it drops below that point.  (Besides, driving at these slower speeds uses substantially less energy.)

So, if I seldom use the carpool lane, even when it is available to me, why did I bother applying for the special decals allowing me to do so?  The other diamond lane available to me is found at metered freeway onramps, where a traffic signal controls which cars enter the freeway and how often.  At some of these metered entrances, a diamond lane has been set up affording carpoolers a shorter wait to get into traffic.  These express ramps can save as much as three to six minutes time getting into traffic on the freeway, and I take advantage of them every chance I get.

How far is 60 miles?

Before buying my Mitsubishi i-MiEV, I read the expected range and then started paying attention to my daily driving habits.  The predicted range for the car is about 62 miles when fully charged (according to the EPA).  That seems quite short, considering that I would refill my gas tank every other week.  My drive to work wasn’t much of a concern because my travel round-trip was about 19 miles, and the planned relocation would double that to nearly 40 miles, both within my car’s range.  My bigger concern was how far I would drive on weekends.  I knew that certain weekend excursions would be beyond the reach of my car, so I ignored those trips.  Instead, I started paying attention to the trip odometer on my gasoline-powered car on weekends.  As it turned out, while I did a lot of driving running errands and such, I seldom drove more than 35 miles in a day, and often less.  So, it seemed that the car can meet the vast majority of my driving needs.

Once I got the car, the next challenge would be to see how far it can drive comfortably without needing a recharge (or only a small one).  My first extended trip was to a wine store about 26 miles to the north, which the car completed comfortably with some miles to spare.  Another time I had to drive to work and back and then to a relative’s place about 6 miles east from home.  After getting to their house, I learned I had to make another trip to another house about 15 miles to the south, and then drive home another 11 miles.  All this was in addition to my usual 40 mile commute.  I drove the freeway on the 15 mile leg, and streets on the 6 mile stretch.  Looking at the charge level, I decided it would be best to take streets home along the last 11 miles.  The 72-mile day left me with 5 miles of range indicated, with the last bar on the charge gauge flashing.  This was my longest drive without recharging.

My challenging trip to Oakland left me very charge nervous.

My third adventure was a little more nerve-wracking.  I needed to pick up a package (yes, more wine) about 37 miles from home to the north in Oakland.  The trip was entirely freeway speed, so I needed to be very careful of the distances.  I knew I could not make the full trip on a single charge, so I found a Target store on the way home that offered charging.  The distance to Oakland and back to Target was just about 60 miles, so I figured I could stop there for two hours, recharge, shop, and get back on the road.  The freeway drive drained more of the battery than I had hoped, so by the time I was looking for the exit to get to Target, the last charge bar was again flashing.  Luckily I had studied the map well and did not miss any turns.  I got to the charger station with 4 miles of range remaining.  But when I tried to start charging, my ChargePoint card was rejected because I hadn’t set up the credit card option.  A panicked phone call resolved that problem but left me with only 80 minutes in my schedule to charge.  By the time I arrived at home, the last bar was again flashing.  Even though I made it safely, I have decided to take my gas car from now on to this place (about twice a year).

Clean Windows and Air

There's no denying that driving an electric vehicle charged by solar panels is doing my bit to minimize my impact on the climate.  But that's not what this post is about.  Driving a gasoline-powered car, you find the world has put in place certain extras to improve your driving experience.  Namely, when you stop at a gas station for a fill-up, you will likely have a squeegee handy to clean your windows and an air pump handy to top off the air in your tires.  When you drive an electric car, you give up gas station visits.  This is a mixed blessing.  True, you get to re-fill (charge) your car from the convenience of your own driveway each night and avoid stops at the gas station on your way home (or rushing to work).  But you lack those little conveniences that help keep driving a safer experience.

Because I park outside, my windshield dews up at night and gathers all the settling dust.  After a few mornings, a haze has formed that I must look through.  After a few more days, I am reminded that I need to clean the windshield every time I drive towards the setting sun.  If I catch this early enough, a few squirts from a bottle of Windex and a clean rag get the windshields back in shape.  The real problem is the tires.  This is where a bicycle pump becomes my upper-body cardio program.  Unlike my VW GTI, with its 225 width tires, the i-MiEV features much smaller 175 width tires in the back and 145 width tires up front.  The advantage these tires offer is that as few as twenty pumps of the bike pump can bring them back from a six PSI deficit.  The rear tires require a little more work, but it’s nothing like the 120 strokes the GTI requires.  If upper body strength (or sweat) is not your thing, then you can either buy an electric air pump, or return to the gas station every other month to top off the tires.  (I’m sure they miss you there and would welcome you back.)  Luckily, you don’t need a paper towel dispenser for checking the oil level each time.

A good-quality bike pump easily keeps the tires up to pressure when used monthly.

Electric Vehicle Rally 2014 and World Record

Today, September 20, 2014, was time for the annual electric car rally put on by the Electric Automobile Association on Silicon Valley.  I had been looking forward to this event for weeks, as it’s my one chance to geek out and see what’s new in EV’s this year.  I had an opportunity to sit in a new Kia Soul electric and to test drive a Fiat 500e.  I found the Fiat to be a bit more “normal” feeling than my Mitsubishi i‑MiEV, but I prefer the interior utility of my car.  There was a converted Porsche convertible from 1958 which had a 60hp motor and lithium-ion batteries.  I also spotted a guy standing on what amounts to a motorized wheel.  The device is controlled via foot actions on the pedals upon which the rider rests.  There were also several companies selling infrastructure or apps related to charging electric vehicles.  But my favorite exhibit remains the electric bathtubs.  These tiny fiberglass bathtub shells, complete with spigots, are little electric cars (along the lines of Barbie’s cars) that kids can drive around in a small coral.  (I was told I could try one, but I was afraid I wouldn’t be able to extract myself afterwards.)

Electric-powered bathtub cars for the kids

Of course, all of these exhibits paled in comparison to the main draw of the event.  It would seem that earlier this year the good citizens of Stuttgart, Germany, got together and assembled a parade consisting of 481 battery electric vehicles (no gas engine hybrids) and made their way into the book of world records.  Earlier this week came word that Silicon Valley was going to break that record.  With little notice, and even less marketing, we cobbled together a band of hundreds of electric cars.  Each car was registered ahead of time and had to present credentials for driving on the road.  We all filled nearly two parking lots at the community college where the event was held.  There were low-flying drones capturing a record of the event, and countless smartphones snapping pictures and videos.  By the time I had arrived, most of the drivers had filled the main parking lot and were overflowing into a second.  Finally came the call to start.  I did some math and estimated that 500 cars spaced 30-feet (front-to-front) would occupy about three miles.  Sure enough, just before my section from the parking lot departed, I could see the first cars arriving from the two-mile loop.  The official count for the parade was 507 electric vehicles, breaking the Stuttgart record by 26.  There was a loud cheer as the officials announced the final tally. 

The official world record plaque

As I was stuck in traffic trying to pull into the parking lot, and during the two-mile loop around the college, I could not help but notice two things.  First, electric cars really are quiet.  There was no droning of gas engines idling, waiting to inch each car forward.  There were no exhaust fumes from the other cars either.  If this is the traffic jam of the future, I’m all for it.  The second thing I noticed was how well electric cars drive at slow speeds.  My gasoline-powered car is a blast to drive at highway speeds and through the mountains because of its manual transmission.  But creeping along at 4 to 6 MPH is a task that wears on your left foot and is anything but smooth.  Likewise, the small rental car I drove last week was jumpy off the start, lurching forward and unable to get going smoothly.  By contrast, the electric car gets going and maintains these speeds easily, comfortably, and quietly.  Again, driving in heavy traffic is best enjoyed in an electric vehicle.  I still prefer the wide-open roads, but now I don’t object so much to congestion.

The parade of all-electric vehicles (including conversions)

The range gauge

When your car carries the equivalent of two or three gallons of gasoline, it is very important to have a good idea how far you can drive without recharging.  Electric car manufacturers understand this and include a driving range gauge.  In the Mitsubishi i-MiEV, the range is displayed by a multi-function gauge that shows eight different measurements, including the outdoor temperature and two different trip odometers.  When I first started driving the i-MiEV, I displayed the range gauge all the time while driving.  This gave me a pretty good idea of how it works.  The gauge reads the battery charge level, then estimates your range based upon the last 5 to 10 miles of driving.  If I finished my day with some city driving, the fully charged car will show 80 to 90 miles of range after charging the battery.  If instead I ended my driving with freeway miles, it will show only 65 to 75 miles of range.  This experience was a little unnerving to watch as the range dropped by 20 miles after having driven only 10 to 12 miles.  This rapid drop happens because the car acclimates to driving on the freeway and lowers its range estimate.  After exiting the freeway, the range stops dropping for a distance and sometimes even increases.

This ever changing impression of how far I can drive lead me to stop using the range gauge.  Instead, I rely mostly on the trip odometer, which I reset after every full charge.  I have learned (and the EPA has confirmed) that the car travels about 4 miles per “tick” (out of 16 ticks) on the charge-level gauge.  The freeway goes a little less per tick, and around town goes a little farther.  To estimate my driving range, I consider where I plan to be driving (city or freeway) and “do the math”.  If I have 9 ticks remaining on the charge, then I figure I can drive about 32 miles on the freeway to 45 miles around town.  Whenever the charge level drops below 4 ticks I switch to the range gauge.  With only 3 or 4 ticks left, I trust the car to know better how far I can drive.

My full-charge range after yesterday's freeway and city driving

So far I have not “turtled” the car or run the battery to empty.  “Turtling” happens when you drain all but a portion of the last remaining charge-level tick.  The car goes into an ultra-conservative energy management mode where the speed is limited to about 25 MPH.  This is indicated on the display using a small turtle graphic.  Because the i-MiEV allows its entire battery capacity to be depleted, turtling the car is not good for the longevity of the battery, though the occasional turtling should not be too harmful.  After about 27,000 miles, the batteries still seem to support the same driving range, so I am guessing that my driving and charging style is good for the car.  (On a similar note, I read that too frequent charging can also be hard on the battery – recharging while in the 25% to 75% charge range is ideal.)

No more gas stations

I always think about how amusing it would be to pull into a gas station in my i-MiEV and ask for help finding where to connect the gas pump.  Somehow, the rational side of my brain says not to do that, so I only visit the gas station on those rare times that I have forgotten to clean the windshield and I’d really like to see out of the car.  That amounts to six or ten visits to a gas station a year.  My new service station is in my driveway. 

Every night, after 9:00pm (when the electric rates drop for me), I plug in the car.  The next morning I awaken to a full charge.  This is the trade-off with a gasoline powered car: no more hanging around the gas station.  The biggest problem is dust and dirt build-up on the wind shield, but that is easy to clean off (if you remember to do it).  Checking the tire pressure is more important in an electric vehicle, and I find that the skinny tires on the electric car need only about a dozen pumps from a bicycle pump each month to keep them maintained.  There is no oil to check.  And best of all, there’s no waiting for a pump.  Of course, I don’t get many opportunities outside of work to interact with the world, and the gas station used to be one of them.  Somebody needs to combine electric-car charging stations with coffee, laundry, and other social activities to get us back into the world.

An ordinary bike pump easily keeps my tired inflated.