Chevrolet 2015 Impala Owner's Manual page 247

9-38 Driving and Operating
To increase vehicle speed in
small increments, briefly press
+RES. For each press the
vehicle goes 5 km/h (1 mph)
faster.
When it is determined that there is
no vehicle ahead or the vehicle is
beyond the selected following gap,
then the vehicle speed will increase
to the set speed.
The speedometer reading can be
displayed in either English or metric
units. See Instrument Cluster on
page 5-9. The increment value used
depends on the units displayed.
Reducing Speed While ACC is at a
Set Speed
If ACC is already activated, do one
of the following:
Use the brake to get to the
desired lower speed. Press the
SET button and release the
accelerator pedal. The vehicle
will now cruise at the lower
speed.
Press and hold the SET button
until the desired lower speed is
reached, then release it.
To decrease the vehicle speed in
smaller increments, briefly press
SET . For each press, the
vehicle goes about 5 km/h
(1 mph) slower.
The speedometer reading can be
displayed in either English or metric
units. See Instrument Cluster on
page 5-9. The increment value used
depends on the units displayed.
Selecting the Follow Distance Gap
When a slower moving vehicle is
detected ahead within the selected
following gap, ACC will adjust the
vehicle's speed and attempt to
maintain the follow distance gap
selected.
Press GAP on the steering wheel to
adjust the following gap. When
pressed, the current gap setting
displays briefly on the instrument
cluster.
Subsequent presses cycle the gap
button through three settings: Far,
Medium, or Near. The gap setting
will be maintained until it is
changed.
Since each gap setting corresponds
to a following time (Far, Medium,
or Near), the following distance will
vary based on vehicle speed. The
faster the vehicle speed, the further
back your vehicle will follow a
vehicle detected ahead. Consider
traffic and weather conditions when
selecting the following gap. The
range of selectable gaps may not be
appropriate for all drivers and
driving conditions.
Changing the gap setting
automatically changes the alert
timing sensitivity (Far, Medium,
or Near) for the Forward Collision
Alert (FCA) feature. See Forward
Collision Alert (FCA) System on
page 9-46.