GMC Sierra Denali 2009 Owner's Manual page 107

To rock the vehicle back and forth to get out of snow,
ice, or sand without damaging the transmission,
see If Your Vehicle is Stuck in Sand, Mud, Ice, or Snow
on page 4-30.
N (Neutral): In this position, the engine does not
connect with the wheels. To restart the engine when the
vehicle is already moving, use N (Neutral) only. Also,
use N (Neutral) when the vehicle is being towed.
CAUTION:
{
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless your
foot is firmly on the brake pedal, the vehicle could
move very rapidly. You could lose control and hit
people or objects. Do not shift into a drive gear
while the engine is running at high speed.
Notice: Shifting out of P (Park) or N (Neutral) with
the engine running at high speed may damage
the transmission. The repairs would not be covered
by the vehicle warranty. Be sure the engine is
not running at high speed when shifting the vehicle.
D (Drive): This position is for normal driving. It
provides the best fuel economy for the vehicle. If you
need more power for passing, and you are:
•
Going less than about 35 mph (55 km/h), push the
accelerator pedal about halfway down.
•
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
D (Drive) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road
driving. You may want to shift the transmission to a
lower gear selection if the transmission shifts too often.
Downshifting the transmission in slippery road
conditions could result in skidding, see "Skidding" under
Loss of Control on page 4-11.
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