Hybrid(I) means a mild hybrid, in which the
electric assist comes from an oversized starter
motor and the IC engine always runs when the
car is moving. PHEV is a plug-in hybrid, able to
run an initial distance on battery power alone —
for instance, a PHEV40 can run approximately
40 miles before the IC engine needs to charge
the batteries. EV is a pure electric vehicle, and
EV100 means it has the battery capacity to run
approximately 100 miles on a charge.
Fuel types include gas, for cars that run on
gasoline. Flex means the car is equipped to use
either gasoline or an ethanol blend (but note
that all modern gasoline cars can be cheaply
modified to run on ethanol). D means diesel,
and these cars can also run on biodiesel. CNG
is compressed natural gas. Li represents lithium-ion batteries, and NiMH is nickel-metal
12k mile CO direct is the approximate
mass of carbon dioxide straight out the tailpipe
in a typical 12,000-mile year of driving, given
12k mile E-mode 100% coal applies to
EVs and PHEVs. It estimates the pounds of
carbon emitted in charging the vehicle for a
12,000-mile year of electric-powered driving if
your electric utility uses coal-burning generation exclusively. Note that, if this is the case,
your EV may produce a bigger carbon footprint
than some modern high-efficiency hybrids.
12k mile E-mode 50% coal estimates the
pounds of carbon emitted in charging an EV
or PHEV for 12,000 miles of electric-powered
driving if your electric utility uses coal-burning
generation for half its delivered electric power.
There is no column for carbon emissions
where electricity is provided from carbon-free sources. In that situation, direct carbon
emission is zero.
12k mile fuel cost is the approximate cost
of fuel for driving 12,000 miles, assuming that
electricity for charging an EV costs 11 cents
per kilowatt-hour, gasoline and CNG costs $2
per gallon and diesel costs $2.15 per gallon. All
these prices are bound to rise over time.
10-year cost is the cost per mile to operate
the vehicle, combining purchase cost and fuel
costs at 12,000 miles per year at today’s prices.
This figure does not include taxes, insurance or
12k CO lbs bio fuel approximates the
pounds of CO emitted if a diesel vehicle oper-
ates on B100 (pure vegetable oil) or a gas/flex
vehicle operates on E85 ethanol.
12k fuel cost bio fuel approximates the
fuel cost to operate a diesel vehicle on B100,
at $2.75 per gallon or a flex-fuel vehicle on E85,
at $1.85 per gallon.
CO per mile bio approximates the pounds
of CO emitted per mile when burning B100
CO per mile fossil approximates the
pounds of CO emitted per mile when burning
petroleum fuel or charging from a coal-burning
Notes on specific cars
Cars are arranged on the chart in the
order of their estimated direct tailpipe CO
emissions. Naturally, the electric vehicles,
with zero direct emissions, are at the top of
the list. The “Generic EVs” are assumed to
be four-passenger sedans. Assuming the battery pack weighs about 800 pounds, lithium
batteries give roughly twice the range as
nickel-metal hydride batteries. A number of
mainstream automakers plan to introduce
sedans in these categories over the next two
to three years.
The Tesla Roadster has been in production for almost a year and has lived up to its
performance claims. In March, the company
unveiled the design for its Model S four-door
sedan, billed as a seven-passenger family vehicle, with a range of 240 miles, at a target price
The original two-seat Honda Insight, discontinued in 2006, is still a great choice as a
commuter car. It may become a collector’s
The Chevy Volt, scheduled for introduction late next year as a 2011 model, is a pure
electric-drive vehicle with an auxiliary flex-fuel IC motor used for charging the batteries
after about the first 40 miles. The term “series
hybrid” describes this technology, in contrast
to “parallel hybrid,” in which both the electric
motor and the IC motor are linked directly to
The Toyota Prius PHEV is available in limited quantities for sale to fleets — or you can
upgrade the Prius you already have to this format for $10,000 to $20,000, depending on the
batteries you choose to add. Note that Toyota
warranties their original factory NiMH battery
pack for 150,000 miles, and the warranty no
longer applies if the car is modified.
The “Generic Theoretical PHEV van” would
be a nine-passenger family van based on the
Toyota Highlander drive train. It might look
something like the Bright van on page 54.
Toyota’s new 2010 Prius is available in
showrooms now, and the claimed 50 mpg performance is achievable in normal driving.
Ford’s new 2010 Fusion Hybrid, already in
dealer showrooms, has been shown to get more
than 41 mpg in highway driving. For now, it’s
by far the most efficient car you can buy from
an American factory and handily outperforms
a number of much smaller cars.
Similarly, the 2009 Volkswagen Jetta TDI
got 48 mpg in a highway driving test by a New
York Times reporter. That’s Prius territory.
Finally, I included my own 13-year-old
Subaru wagon. Driving carefully, I can milk
30 mpg from this beast, even with AWD
and snow tires. It simply shows that a smallish engine and conservative design make for
more efficient operation than you’ll get from
any existing hybrid SUV. ST
solartoday.org SOLAR TODAY June 2009