On Feb. 1, the U.S. Environmental Protection Agency (EPA)
rolled out a proposal to revamp its fuel economy tests, which tell consumers
what mileage per gallon to expect from their new vehicles. In recent years,
consumer groups and a number of car companies have joined environmental groups
in calling for the overhaul, which is expected to take effect for model year
2008 cars.
Each year, EPA publishes a guide listing the fuel efficiencies of new cars,
SUVs and light trucks. As mandated by federal law, labels on new car windows
represent the gas mileage achieved in the EPA tests, which incorporate a weighted
average of city to highway driving (55 percent to 45 percent, respectively),
as measured in a constant-temperature lab (see Geotimes,
November 2004).
The tests, however, are outdated and a poor measure of actual fuel use, says
Lee Schipper, head of research at the World Resources Institute’s EMBARQ
program in Washington, D.C., who published comparisons of fuel-economy standards
for several countries in Transparent Policy in 1994. EPA’s tests were designed
in the 1970s, and have not been modified since 1985, when EPA itself began adjusting
its mileage 10 to 22 percent downward on the window stickers, to more accurately
represent the mileage that consumers would get from their cars.
Bluewater Network, an environmental watchdog that petitioned EPA to revise its
testing standards, says that EPA’s numbers are off by as much as 34 percent.
Schipper says that the tests vastly underestimate the amount of time spent in
city or congested driving, and they do not account for actual road conditions
such as hills, curves and cold temperatures, or for the use of accessories such
as air conditioning.
The tests also do not take into account changes in driver behavior, such as
driving faster, Schipper says. No matter what, though, “the mileage will
never exactly match what the stickers say because it is impossible to predict
actual human behavior.”
In trying to “reflect changes in the way we drive,” three new tests
will be run in addition to the standard highway and city driving simulation
tests, says John Millet, a spokesman for EPA. The new tests are designed to
capture factors that can significantly affect fuel economy: faster driving,
more rapid acceleration, cold weather and the use of air conditioning, he says,
as well as other car and road conditions.
EPA expects that fuel-economy estimates on new cars will likely be 10 to 20
percent lower due to the new tests, with estimates potentially 20 to 30 percent
lower for hybrids. The agency will also modify its message on the actual stickers
to better caveat the estimated mileage. “It is important for consumers
to understand that their mileage will vary, depending on the driver, the road
conditions and so on,” Millet says. “The single greatest variability
is the foot of the driver on the accelerator.”
The revised tests and stickers are a step in the right direction, Schipper says,
but “they will need to be checked again in a year or two.” Consumers
need to realize, he adds, that EPA’s fuel-economy estimates are just that
— estimates — and are designed to offer only a point of comparison
between different cars. It remains to be seen, he says, whether the new tests
change fuel-economy rankings between different cars, which might cause a stir
in the auto industry.
The EPA-proposed tests are open for public comment until the end of this month.
Megan Sever
Links:
"Fuel economies, Part II," Geotimes,
November 2004
U.S.
Environmental Protection Agency Fuel Economy information
FuelEconomy.gov
EMBARQ
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