Pontiac 2008 G5 Owner's Manual page 100

If you cannot shift out of PARK (P), ease pressure on
the shift lever and push the shift lever all the way
into PARK (P) as you maintain brake application. Then
press the shift lever button and then move the shift
lever into another gear. See Shifting Out of PARK (P)
(Automatic Transmission) on page 2-35.
REVERSE (R): Use this gear to back up.
Notice: Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.
To rock your vehicle back and forth to get out of snow,
ice, or sand without damaging your transmission,
see If Your Vehicle is Stuck in Sand, Mud, Ice, or Snow
on page 4-24.
NEUTRAL (N): In this position, your engine does not
connect with the wheels. To restart when you are
already moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
2-28
CAUTION:
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Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless
your foot is firmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.
Notice: Shifting out of PARK (P) or NEUTRAL (N)
with the engine running at high speed may damage
the transmission. The repairs would not be
covered by your warranty. Be sure the engine is not
running at high speed when shifting your vehicle.