Cadillac 2011 DTS Owner's Manual page 129

Use this gear to back up.
Also use this gear 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 5 17 for additional
information.
In this position, the engine does not
connect with the wheels. To restart when you are
already moving, use N (Neutral) only. Also, use
N (Neutral) when the vehicle is being towed.
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.
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 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.
The transmission will shift down to the next gear
and have more power.
Downshifting the transmission in slippery road
conditions could result in skidding, see Skidding under
Loss of Control on page 5 10.
D (Drive) can be used for towing. You may want to shift
the transmission to 3 (Third) or, if necessary, to a lower
gear if the transmission shifts too often under heavy
loads and/or hilly conditions.
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