GMC 2008 Yukon Denali Owner's Manual page 130

DRIVE (D): This position is for normal driving. It
provides the best fuel economy for your vehicle. If you
need more power for passing, and you are:
•
Going less than about 35 mph (55 km/h), push your
accelerator pedal about halfway down.
•
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
DRIVE (D) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road
driving. 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 4-12
When temperatures are very cold, the Hydra-Matic
Automatic Transmission's gear shifting may be delayed
providing more stable shifts until the engine warms
up. Shifts may be more noticeable with a cold
transmission. This difference in shifting is normal.
MANUAL MODE (M): This position lets drivers select
the range of gears appropriate for current driving
conditions. See Range Selection Mode later in
this section.
2-32
Notice: Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator
pedal may damage the transmission. The repair will
not be covered by your warranty. If you are stuck,
do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
Your vehicle has a shift stabilization feature that adjusts
the transmission shifting to the current driving conditions
in order to reduce rapid upshifts and downshifts. This shift
stabilization feature is designed to determine, before
making an upshift, if the engine will be able to maintain
vehicle speed by analyzing things such as throttle
position, vehicle load, and hill grade. If the shift
stabilization feature determines that a current vehicle
speed cannot be maintained, the transmission does not
upshift and instead holds the current gear. In some
®
cases, this may appear to be a delayed shift, however the
transmission is operating normally.
Your vehicle's transmission uses adaptive shift controls.
Adaptive shift controls continually compares key shift
parameters to pre programmed ideal shift conditions
stored in the transmissions computer. The transmission
constantly makes adjustments to improve vehicle
performance according to the way the vehicle is being
used, such as with a heavy load. During this adaptive
shift controls process, some shifts may feel different as
the transmission determines the best settings for a
particular shift.