GMC 2007 Acadia - Manual (Page 355)

{ CAUTION:
Coasting downhill in NEUTRAL (N) or with
the ignition off is dangerous. The brakes
will have to do all the work of slowing
down. They could get so hot that they
would not work well. You would then have
poor braking or even none going down a
hill. You could crash. Always have the
engine running and your vehicle in gear
when you go downhill.
• Know how to go down hills. The most
important thing to know is this: let the engine
do some of the slowing down. Shift to a
lower gear when you go down a steep or
long hill.
• Know how to go uphill. You may want to shift
down to a lower gear. The lower gears help
cool the engine and transmission, and you can
climb the hill better.
• Stay in your own lane when driving on
two-lane roads in hills or mountains. Do not
swing wide or cut across the center of the
road. Drive at speeds that let you stay in your
own lane.
• As you go over the top of a hill, be alert.
There could be something in your lane,
like a stalled car or an accident.
• You may see highway signs on mountains
that warn of special problems. Examples
are long grades, passing or no-passing zones,
a falling rocks area, or winding roads.
Be alert to these and take appropriate action.
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