Ford Automobile User Manual page 122

Driving
When to use D (Drive)
The D (Drive) position eliminates
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the needless shifting back and forth
between third and fourth gears that
your vehicle may do when driving
on hilly terrain. It also gives more
engine braking than overdrive to
slow your vehicle on downgrades.
1 (First)
Use 1 (First) for when added engine
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braking is desired when descending
steep hills.
The automatic transaxle will shift to
the proper gear to ascend any grade
without any need to shift to 1
(First).
Do not go faster than 61 km/h (38 mph) when in this gear. You can
upshift from 1 (First) to overdrive at any time.
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