From Gas Guzzler to Fuel Miser
It started with a used 1967 Plymouth Barracuda. Bob
DeVault, an engineer and strategic planner in the Energy
and Transportation Science Division, knew that when the
gas mileage started declining on his first car, it was an
indication that the Barracuda might need a tune-up. So he
faithfully tracked his gas mileage. After the introduction
of fuel injected-engines, gas mileage was no longer the
best indication of the need for maintenance. But the habit
was established, and DeVault continues to record every
gallon of gas he buys and his mileage.
DeVault confesses, “I was “hooked on sports cars before I was old enough to get a driver‟s
license. I have always preferred fun-to-drive performance cars. My first, second, and third cars
(the Barracuda, a Datsun 240Z, and a 12-cylinder Jaguar XKE) were purchased before the first
„energy crisis‟ when gasoline was $0.32 per gallon.” He found a kindred spirit in his wife
(ORNL retiree Julie Watts), who had purchased a COPO Camaro, owned an airplane, and
volunteered as a race car mechanic—and shared
his love of performance cars.
Improved technologies allow new cars to perform
well, provide extra safety, be more fuel-efficient,
and reduce pollution. DeVault puts his highest
priority on energy security—reducing America‟s
dependence on foreign oil. Since the 1970s, the
family has tried to purchase the most fuelefficient and reliable vehicle in each type of
vehicle they have owned (sports car, full-sized
van, mini-van, four-wheel drive sports-utility
vehicle, and four-door family sedan).
When some friends at ORNL were working on
the fueleconomy.gov website for DOE and the
EPA, they needed a beta tester for a new feature
that would let you record your gas mileage on the
site and see how it compared to the mileage
others were getting. DeVault started recording the
mileage online for each of his cars and has
Bob DeVault’s "garage" on the website
fueleconomy.gov, where he records mileage
continued to do so. His 1990 Mazda Miata was
on his family's cars
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recognized as the car with the most gas mileage data recorded on the site during a MotorWeek
feature on fueleconomy.gov. He also has the distinction of having the first second-generation
Prius and the first Nissan Leaf listed on the site.
Because his primary concern is energy security,
DeVault doesn‟t insist that the premium he pays
for a highly efficient car be recovered in a few
years in lower fuel cost. He points out that
automobiles are routinely sold with “optional
equipment” important to the buyer which have no
simple economic payback. The Toyota Prius is
initially more expensive than similar family cars.
But he points out that Consumer Reports
estimates the total ownership cost of the Prius
over 5 years is lower than other cars.
Bob DeVault with Prius in 2007
DeVault has owned a Nissan Leaf electric vehicles for about 3 months. The DeVault family
drives about 30,000 mi annually, while the Leaf is accumulating about 1000 miles/month. The
Leaf gets a mixture of suburban and highway driving, with not much stop-and-go city driving.
He has installed a home version of the ECOtality BLINK 240-volt charging station at his house.
Based on the first 2000 miles, the Leaf used $46.76 of electricity (residential rate), while the
Prius would have cost $164.98 for gasoline and his Highlander would have cost $371.21
($3.65 per gallon).
Having a more efficient car has not encouraged him to increase his driving. His choice has been
to use the Leaf for his daily commute—electricity instead of gasoline. He finds the Leaf very
quiet and vibration-free (only an electric motor) and thinks it handles and rides better than his
Prius, due to the lower center of mass created by the heavy battery. The electric motor produces
a lot of torque immediately, not hesitating or waiting for a conventional the engine or
transmission to respond, reminding him of the 12-cylinder Jaguar‟s performance under 45 mph
(effortless, quick acceleration). In most cases with hybrid cars, the battery lasts for the life of the
car.
The main disadvantage of the Leaf is the limited
driving range. Most of the time, DeVault only
charges his battery to 80% capacity—this is
supposed to extend the life of the battery—which
limits his range to about 60 miles on a charge with
a comfortable reserve.
The availability of onsite charging at ORNL has
expanded his comfortable daily travel range to
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Leaf being charged at ORNL's solar-assisted
charging station
more than 90 miles, while maintaining an 80% maximum charge. This range allows for a roundtrip to ORNL and to the University of Tennessee. He foresees a challenge this winter, if he
leaves work, drives home to pick up his wife, goes to Lady Vol basketball games, and then
returns home. Currently, while DOE co-sponsored Electric Vehicle Project continues, he charges
the Leaf free at ORNL, saving an average of $1.18 a day on his home electric bill.
What advice would he have for people
trying to find a fuel efficient car? First,
decide what kind of vehicle you need.
Consider the total cost of ownership, not
just the initial cost. Then buy or lease the
most efficient vehicle that meets your
needs.
If you have only one vehicle, the range
limitation on electric vehicles, such as the
Why has this electric Leaf pulled into a gas station?
Leaf, disqualifies them for most people.
(Bob DeVault needed to get diesel fuel for his
But DeVault feels they make an excellent
tractor.)
second or third car. He suggests
considering a hybrid or an electric car, even if the pay back in fuel savings is not obvious. An
electric car does not use oil or gas directly, a plus for energy security, and requires very little
maintenance compared to a conventional car.
A hybrid, plug-in hybrid, or extended range electric vehicle (e.g., Chevy Volt or Fisker Karma)
should work as an only car. Hybrid technology has improved. The second generation Prius was
bigger, more powerful, and more efficient, making it a competitive family sedan. DeVault says
he has consistently gotten more than 40 mpg on the highway on long trips in the Prius (46 mpg
overall). If you are unsure about buying a hybrid or an electric car, try out a hybrid, Volt, or Leaf
by leasing first (as DeVault did for his first Prius).
The Leaf, Volt, Tesla, Fisker, and other planned plug-in vehicles are currently eligible for
substantial federal tax credits and some state incentives. DeVault received $10,000 in tax credits
and incentives (federal and Tennessee) and a free home charging station (worth about $2,000) as
part of the Electric Vehicle Project. This brought the initial cost of his Leaf into the same range
as a comparable conventional vehicle, while costing much less for fuel every month. DeVault
also notes that the ORNL Federal Credit Union offers a lower interest rate for the purchase of
“green vehicles.”
After over 40 years of tracking his gas mileage, DeVault finds it nice when his effort is
appreciated. One day, he was stopped at a red light in Lenoir City, when four Harley-Davidson
motorcycles pulled up next to him. The burly bikers were clad in leather and had on headset
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microphones. One biker noticed the Leaf and alerted the others, who also looked it over. When
the light changed, all four motorcyclists gave the Leaf a “thumbs up” before moving on.
More Information
The website fueleconomy.gov is an excellent resource for comparing vehicle efficiencies and
other energy-related information. A number of publications by ORNL‟s David Greene are also
valuable sources of information on a variety of subjects, from efficient driving techniques to
energy technology policy to world oil supply.
September 2011
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