Chevrolet 2008 Impala, Owner'S Manual, Page: 103 / 400

THIRD (3): This position is also used for normal driving.
However, it reduces vehicle speed more than DRIVE
(D) without using your brakes. You might choose THIRD
(3) instead of DRIVE (D) when driving on hilly, winding
roads, when towing a trailer, so there is less shifting
between gears and when going down a steep hill.
SECOND (2): This position reduces vehicle speed
even more than THIRD (3) without using your brakes.
You can use SECOND (2) on hills. It can help control
your speed as you go down steep mountain roads.
You would also then want to use your brakes off and on.
Notice: Driving in SECOND (2) for more than
25 miles (40 km) or at speeds over 55 mph (90 km/h)
may damage the transmission. Also, shifting into
SECOND (2) at speeds above 65 mph (105 km/h) can
cause damage. Drive in THIRD (3) or DRIVE (D)
instead of SECOND (2).
FIRST (1): This position reduces vehicle speed even
more than SECOND (2) without using your brakes.
You can use it on very steep hills, or in deep snow or
mud. If the shift lever is in FIRST (1) while the vehicle is
moving forward, the transmission will not shift into
first gear until the vehicle is going slowly enough.
Notice: Spinning the tires or holding the vehicle
in one place on a hill using only the accelerator
pedal may damage the transmission. The repair will
not be covered by your warranty. If you are stuck,
do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
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