Subaru 1999 Forester Owner's Manual page 191

At state inspection time, remember to tell your inspection or service
station in advance not to place your Subaru AWD vehicle on a two-
wheel dynamometer. Otherwise, serious transmission damage will
result.
Some states have started using dynamometers in their state inspection
programs in order to meet their obligation under federal law to implement
stricter vehicle emission standards to reduce air pollution from cars. A
dynamometer is a treadmill or roller-like testing device that allows your
car's wheels to turn while the car remains in one place. Depending on
the severity of a state's air pollution problems, the states must adopt
either a "basic" or "enhanced" vehicle emission inspection test. Nor-
mally, a portion of the basic emission test consists of an emission
inspector inserting an analyzer probe into the exhaust pipe of an idling
vehicle for a short period of time. States with more severe air pollution
problems are required to adopt an enhanced vehicle emission test. This
test simulates actual driving conditions on a dynamometer and permits
more accurate measurement of tailpipe emitted pollution than the basic
emission test.
The U.S. Environmental Protection Agency (EPA) and states using two-
wheel dynamometers in their emission testing programs have
EXEMPTED Subaru AWD vehicles from the portion of the testing pro-
gram that involves a two-wheel dynamometer.
There are some states that use four-wheel dynamometers in their testing
programs. When properly used, that equipment will not damage an AWD
Subaru vehicle.
Under no circumstances should the rear wheels be jacked off the
ground, nor should the driveshaft be disconnected for state emission
testing.
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