What Kind of Car?
ILEA Leaf #10
You're concerned about the environment, but you need to drive. Which car will
do the least damage? There's no easy answer, and you will have to make some
tradeoffs between your budget and your determination to help change the world.
But you will also need to think about what "changing the world" means to
Is it more important to (a) help reduce future emissions an uncertain
amount by investing in advanced technology or (b) reduce immediate emissions a
known amount with existing technology?
Is it more important to (a) fight climate change and foreign oil dependence
by reducing fossil fuel use or (b) help clean the air in your region by
reducing traditional pollutants from the car tailpipe?
At ILEA we are all about life-cycle assessment, so we like to take the big
picture approach: advancing technology trumps personal emissions, and greenhouse
gases trump local pollutants. If you answer the questions differently, keep
those differences in mind as you read through our recommendations; near the end
of the email there's a comparison table to help you do this.
Below are five basic choices you can take, beginning with the most
conventional and ending with the most adventurous. We think the most
adventurous steps probably have the most impact on the big picture, but if you
answered the questions differently than we do, you may want to take one of the
#5: High-efficiency conventional cars
If none of the more advanced options meet your needs, then you can still
reduce both your greenhouse gas and your traditional pollutant emissions by
being careful to choose a car with the highest fuel economy. Keep in mind
though, this option will do little to advance new technologies.
The U.S. EPA's fuel economy website
provides comparative ratings of nearly all cars available in the U.S. The
American Council for an Energy Efficient Economy publishes the Green Book, which provides even more
detailed environmental information. Though the EPA website is free, the Green
Book is not: a month of access costs $8.95.
Diesel engines are on average more efficient than gasoline engines. Just as
one example, a manual transmission, 2005 VW Jetta Wagon is rated 36 city and 47
highway. In the United States we tend to think of diesel cars as dirty, and
indeed historically the tailpipe emissions have been much worse than for
gasoline cars. But beginning in mid-2006 all automotive diesel fuel in the U.S.
will be ultra-low
sulfur, allowing better emissions control and eliminating nearly all of the
irritating exhaust fumes we normally expect from diesel engines. That means
beginning in 2007, many diesel vehicles will be preferable to their gasoline
counterparts. Also, if you choose a diesel vehicle, you will always be able to
leapfrog to the much more aggressive biodiesel solution, #3 below.
#4: Gasoline-electric hybrids
Gasoline-electric hybrids (usually just called "hybrids") have by far been
the most popular choice of environmentally conscientious car buyers over the
past few years. Hybrids are fueled at the gas pump just like any other
gasoline-powered car, but boast particularly impressive mileage (the 2005 Toyota
Prius does 60 city and 51
A hybrid car has both a gasoline engine and an electric motor, but it does
not need to be plugged in. The gasoline engine takes care of charging the
electric motor's battery. The battery is also charged when the driver steps on
the brakes: the electric motor works in reverse to stop the wheels by converting
their rotational energy to electricity saved in the battery. Hybrids also cut
out the gasoline engine when the car drives very slowly or stops, minimizing
energy wasted in idling.
Gasoline-electric hybrids are an excellent choice for the environmentally
aware consumer. Because of their high fuel economy, hybrids reduce both
greenhouse gases and traditional pollutants, like any other high-mileage
vehicle. But buying a hybrid gives the environment an extra boost because you
are helping introduce an important, cutting-edge technology. So far, Honda and
Toyota have released hybrid passenger cars, and Ford has released a hybrid SUV.
You can expect to see many more models appear over the coming few years.
You can nearly eliminate your greenhouse gas emissions by buying an ordinary,
high-efficiency diesel vehicle and filling the tank with biodiesel. Biodiesel is
made from recycled vegetable oils or from by-product oils of crops grown for
other purposes. The net greenhouse gas emissions from making the biodiesel are
extremely low, and when burned in a diesel engine biodiesel is cleaner at the
tailpipe too. As of early 2005, biodiesel sells for about $1 more
per gallon in the U.S. (on average) than fossil diesel, but a new federal tax
credit promises to lower the price down to nearly the same as fossil diesel.
With this choice you are boosting the toddler biodiesel fuel industry.
Biodiesel will always be an environmental niche product, because there is not
enough land area in the U.S. to grow crops for the entire vehicle fleet.
Still, it may be an important part of a future transportation solution. Because
your car will always be able to burn fossil diesel fuel, it is important that
you are committed to the effort to buy biodiesel, even if it means going
out of your way each time you need to refill your tank. Before you make this
choice, make absolutely sure that biodiesel is available in
your area. If it isn't and you are particularly excited about
biodiesel, get together with some other enthusiasts and you can make your own.
#2: Electric cars
A warning here. Once you step past option #3, biodiesel, you are stepping
into the realm of the difficult, the expensive and oftentimes the nerdy. You may
end up importing cars or car parts from other states or even countries, and
engineering skill (or at least the skills necessary to talk to engineers) can
get you more of what you want in a custom car. If you feel motivated for a
technical adventure, read on.
Electric cars are falsely perceived as short in performance and short in
range. In fact, electric cars can be stunning performers, as members of the National Electric Drag Racing Association will
be all too happy to tell you (or show you). Though performance limitations are
pure myth, range limitations are real. But recent advances in lithium-ion
battery technology are bringing 300 mile
ranges within reach.
Electricity is not
always the best environmental choice. Though the car is zero-emissions on
the road, the electric generator can sometimes be a terrible emitter of both
greenhouse gases and traditional pollutants, especially if you live in a coal
state. Fortunately, there is a solution. You can make sure to buy
exclusively green electricity to charge
your car; electricity is so much cheaper than gasoline that even the slightly
more expensive green electricity will still come in well under the cost of
Even without using green electricity, promoting electric cars has an enormous
value for long-term energy policy. Electricity is by far the best way to get renewable
resources to cars, and helping to get electric cars onto the market is an
important enabling step for renewable energy in general. If you want to buy an
electric car, start by visiting the Electric Drive Transportation
#1: Plug-in hybrids
Driving a plug-in hybrid is probably the most edgy and policy-advancing
choice you can make, but getting your hands on a plug-in hybrid will make buying
an electric car look like a piece of cake: there are no commercial models
available in the United States.
A plug-in hybrid is similar to a gasoline-electric hybrid, but it has a
larger battery and can be plugged into a wall socket as well as fueled with
gasoline. The plug-in hybrid can drive entirely on electric energy for twenty,
thirty or forty miles depending on how large the battery is. Because most people
use their cars for commutes of a few tens of miles at the most, a plug-in hybrid
that is recharged each night can run almost exclusively on electricity, kicking
in the gasoline engine only for longer trips.
Though you can't buy one, a sufficiently motivated enthusiast can convert a Toyota Prius to
plug-in mode – at a steep cost. If you lack either the money or the technical
savvy to do that, best just stay
in tune with the evolving technology, and wait for your chance to buy one
off the shelf.
Why is ILEA advocating a plug-in hybrid as the most edgy choice, when
all-electric cars might seem more like the ultimate goal for transportation
technology? Though engineers are well on their way to solving the all-electric
range problem, they're not there yet. Plug-in hybrids are an extremely valuable
bridge technology, because they retain the convenience of unlimited range that
consumers are used to, while simultaneously advancing the large automotive
batteries that can be the foundation for all-electric cars.
But maybe plug-in hybrids are in fact the best, ultimate goal for sustainable
transportation. An advanced, plug-in hybrid with a 100 mile range would need to
be fueled only a few times a year, in most cases. Such a low rate of liquid fuel
consumption, if it pervades the car market, would enable us to fuel all of our
vehicles with a renewable liquid fuel like ethanol or biodiesel, getting the
best of both approaches.
#4: gasoline-electric hybrids
#2: electric cars
#1: plug-in hybrids
Comparing the five options on the basis of advancing
technology, reducing greenhouse gases, and reducing traditional pollutants. ++
excellent performance + good performance +/- ambiguous performance, all relative
to a typical, 2005-model year, U.S. automobile.
#0: No car at all
Even a zero-emissions car results in environmental impacts from generating
the electricity or biofuel that powers it; upstream emissions from the car
manufacturing plant; and indirect impacts from the roads and parking lots that
support it. The best car is no car. If you can avoid purchasing a car by using
one or more of the alternatives below, you will have the biggest personal impact
on the environment possible:
- carpooling can easily triple your fuel economy on a per-passenger
- using vanpools or public transit saves gas and saves you
- car-share programs might give you just enough access to a vehicle
that you don't have to buy one;
- combining your trips saves you time as well as gas;
- living in an urban neighborhood near your workplace, shops and
other resources can eliminate most of your car trips;
- and of course, anytime you can walk or bicycle instead of
drive, take the opportunity to get some healthy exercise!
 Some of you may
notice the absence of "flexible-fuel" vehicles that can accept either gasoline
or ethanol. ILEA is not promoting this solution because most ethanol available
in the U.S. is starch-based, inefficiently using only a portion of the crop
(usually corn) that generates the ethanol. Flexible-fuel vehicles will make more
sense once cellulosic ethanol, which makes efficient use of the entire plant,
becomes more widely available. Also, "flexible-fuel" vehicles are not a
significant technological advance: their design is nearly identical to an
ordinary, gasoline-fueled car.
 Hybrids have the
curious property of achieving better mileage in-city than on the highway. The
hybrid technology can take great advantage of the slow, stop-and-start driving,
but is incapable of mitigating the wind resistance at highway speed.
 Office of
Transportation and Air Quality. A Comprehensive Analysis of Biodiesel Impacts
on Exhaust Emissions. Washington, DC. U.S. EPA. 2002. EPA420-P-02-001.
 Charles L.
Peterson. Potential Production of Biodiesel. University of Idaho.
 In some areas you
may be limited to blends of biodiesel with fossil diesel. Blends
are labeled with "B" numbers, for instance B20 is a blend of 20%
biodiesel with 80% fossil diesel, B100 is 100% biodiesel (pure
or "neat" biodiesel). In cold climates a blend may be necessary,
because without additives B100 begins to gel around 32 degrees
F, while B20 won't begin to gel until as low as 7 degrees F.