Toyota Lexusc Owner's Handbook Manual page 495

STARTING AND DRIVING
The vehicle-to-vehicle distance is always set to LONG when
the ignition switch is turned on.
Select the vehicle-to-vehicle distance considering traffic
conditions. The approximate vehicle-to-vehicle distance
based on time interval when driving at 88 km/h (55 mph) is
shown below:
LONG . . . . . . . . . about 75 m (245 ft.)
MIDDLE . . . . . . . about 50 m (165 ft.)
SHORT . . . . . . . about 30 m (100 ft.)
If the vehicle speed is slower than 88 km/h (55 mph), the
distance will be shorter than the above.
During long downhill driving, the vehicle-to-vehicle distance
will be shorter than the selected distance.
476
(i) Braking control
Dynamic laser cruise control is not a collision avoidance
system. If the approach warning is activated, depress the
brake pedal to decelerate to ensure an appropriate
vehicle-to-vehicle distance.
If you are getting closer to the vehicle ahead at a relatively
higher speed than that of the vehicle ahead or if engine braking
cannot be applied properly, braking control is automatically
activated. At this time, the display flashes.
Braking control is operating only when the vehicle-to-vehicle
distance control mode is selected and your vehicle speed
exceeds about 40 km/h (25 mph). If the speed decreases
below about 40 km/h (25 mph), braking control will cease,
requiring the manual application of brakes.