Toyota Lexusc Owner's Handbook Manual page 486

(a) Dynamic laser cruise control operations
STARTING AND DRIVING
The dynamic laser cruise control function operates
automatically and depending on whether a vehicle is
detected ahead may change the speed of your vehicle as
follows.
If no vehicle is running ahead of you —
1 Cruising at a fixed speed: If there is no vehicle detected
ahead, your cruising speed is maintained at the preset
speed from about 45 km/h (28 mph) to about 135 km/h (85
mph). The preset speed is displayed in the display. For
the vehicle speed setting, see "(c) Setting the desired
speed" on page 472.
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