IEEE Spectrum July, 2014 - 27

Joe WiNgerd

Fill 'er uP: During winters, the author [right] found
that the Ford C-Max Energi's range suffered. During
the day, he can top up the batteries at a charging
station installed at his office [opposite page].

discount purchasing plan that brought down the
total cost of the car to $32,000. I also rationalized that just like my solar panels, the car would
reduce my family's carbon footprint a little more.
Drivers can operate the Energi in one of three
modes: EV Now (car uses batteries if possible),
EV Later (car uses the gasoline engine), or Auto
(car decides which mode to use).
I took delivery of the car a few weeks before
Thanksgiving, just in time for a 2,900-km family
trip. We left on a cold morning, and I was really
hoping we would make it to Kansas City, Mo.-
1,000 km away-on one tank. Early into the trip, it
was clear that we didn't have a prayer. The batteries helped only for the first 30 km or so, and the
engine wasn't as fuel efficient as I'd hoped. Our
first tank returned 7.30 L /100 km (32.2 mpg).
For the average car this is great efficiency, but for
a plug-in it was well below expectations. Clearly,
this hybrid did not like the interstate. Over our entire trip, we averaged 6.94 L /100 km (33.9 mpg).
I was getting pretty depressed.
Back in Boulder, we started using the car for
commuting to and from work. We plugged in every night and drove about 22 km each day. I dug
out my Kill A Watt power meter to check how the
car was charging. With the 120-V charger, the
car took 8.18 kWh for a full overnight charge. After 21 days of commuting, our fuel efficiency hit
3.05 L /100 km (77 mpg)! However, as winter set
in and we began to use the car's heater, the
estimated battery power range would drop
from 32 km to about 21. Owning a plug-in
brings new meaning to the words "your mileage may vary."
By far the biggest disappointment has been
the Sync entertainment system, a partnership between Ford and Microsoft. The result
is dreadful. The simple act of playing the radio
has been turned into a high-tech mess. The
display on the screen is unreliable: Sometimes
it shows buttons labeled with our preprogrammed stations; at other times the buttons
are blank. The media input menu occasionally
disappears. The clock randomly scrambles
the hours and minutes. I could go on.
One thing Ford did get right is providing feedback to the driver. With my old

Volkswagen Beetle, the only way to measure
fuel consumption is with the odometer and a gas
station receipt. The Energi measures just about
everything: distance traveled, distance traveled
in EV mode, fuel consumed per trip, kilowatthours consumed, range added from regenerative braking, and even my "brake score" (how well
I did braking and getting the energy into the batteries). From this feedback I can see, for example,
that routes with significant uphill sections result
in worse fuel efficiency than flat routes.
Over the year, we did not achieve the fuel
economies I had modeled with my spreadsheet.
Two factors hurt my estimate: Highway fuel
efficiency was 20 percent lower than the official U.S. Environmental Protection Agency figure,
and cold weather with the heater active reduced

a year's worth of driving data
total distance

26,131 km

Ev-only distance

14,352 km

regenerative braking distance
average charge

6 kwh

Electricity used for charging
Electricity cost

809 km

1,734 kwh
us $191

Fuel used

1,132 l

Fuel cost

$1,041

Fuel efficiency

4.34 l/100 km (54.24 mpg)

the range by 35 percent [see the table, "A Year's
Worth of Driving Data," for my overall results].
Thanks to my house's solar panels, my electricity was free, making the cost per kilometer
around $0.040, compared with my Nissan
Altima's $0.082/km. Not quite the savings I had
estimated, but a good improvement. In addition,
my office has put a charging station in the parking lot, which could potentially let me run a year
on the same tank.
One interesting issue with driving an electric
car is how quiet it is. It's nearly impossible to tell
from noise or vibration when the engine starts
and stops: Only if you accelerate hard and rev
the engine can you hear it labor. Driving around
a parking lot, for instance, I frequently find myself creeping along behind pedestrians who
are oblivious to the car's presence. The
U.S. government has been talking about
requiring EV cars to produce a sound, which
makes sense. But what kind of sound? I'd
love to have the sound be programmable-
I can just imagine my car mooing its way
through the parking lot. And a traffic jam of
EVs sounding like a herd of cattle would be
really funny.
It makes little sense to use a plug-in to tow
a boat or a heavy trailer. But plug-ins shine
in short-distance commuting. In the C-Max
Energi, I think Ford has built a practical family car with decent EV range.
-STeven a. JohnSon

Read an extended version of this article
online at http://spectrum.ieee.org/phev0714

sPecTruM.Ieee.orG

NorTH AMerIcAN

jul 2014

http://spectrum.ieee.org/phev0714 http://sPecTruM.Ieee.orG

Table of Contents for the Digital Edition of IEEE Spectrum July, 2014