Buick Lucerne 2007 Owner's Manual page 120

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 move the shift lever into the gear you want.
See Shifting Out of Park (P) on page 125.
REVERSE (R): Use this gear to back up.
Notice: Shifting to REVERSE (R) while your
vehicle is moving forward could damage the
transaxle. 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
transaxle, see If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow on page 306.
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.
120
CAUTION:
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Shifting into a drive gear while your
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) while the engine is running at
high speed may damage the transaxle.
The repairs would not be covered by your
warranty. Be sure the engine is not running at
high speeds when shifting your vehicle.