GMC 2012 Sierra Denali Owner's Manual page 286

9-36 Driving and Operating
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.
WARNING
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 55 km/h
(35 mph), push the accelerator
pedal about halfway down.
Going about 55 km/h (35 mph) 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 driving
off-road. 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 9 5.
When temperatures are very cold,
the transmission's gear shifting may
be delayed in providing more stable
shifts until the engine warms up.
Shifts may be more noticeable with
a cold transmission. This difference
in shifting is normal.