Subaru 2002 Legacy Owner's Manual page 306

Starting and operating
When the difference between the actual vehicle speed and the set
speed is less than 4 mph (6.8 km/h), the set speed can be lowered 1
mph (1.6 km/h) each time by pressing the control lever downward in
the "SET, COAST" direction quickly within a half second.
n To decrease the speed (by brake pedal)
1. Depress the brake pedal to release cruise control temporarily.
2. When the speed decreases to the desired speed, press the control
lever downward in the "SET, COAST" direction once. Now the desired
speed is set and the vehicle will keep running at that speed without
depressing the accelerator pedal.
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