Hummer 2003 H2 Owner's Manual page 107

CAUTION:
Shifting into a drive gear while your engine is
"racing" (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. Don't shift
into a drive gear while your engine is racing.
NOTICE:
Damage to your transmission caused by shifting
out of PARK (P) or NEUTRAL (N) with the
engine racing isn't covered by your warranty.
DRIVE (D): This position is for normal driving. If you
need more power for passing, and you're:
D
Going less than about 35 mph (55 km/h), push your
accelerator pedal about halfway down.
D
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
You'll shift down to the next gear and have more power.
DRIVE (D) can be used when towing a trailer, carrying
a heavy load, driving on steep hills or for off
driving. You may want to shift the transmission to
THIRD (3) or, if necessary, a lower gear selection if the
transmission shifts too often.
THIRD (3): This position is also used for normal
driving, however it offers more power and lower fuel
economy than DRIVE (D).
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road
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