Toyota Lexusc Owner's Handbook Manual page 487

STARTING AND DRIVING
If a vehicle is detected ahead of you —
2 Deceleration cruising function: If a slower moving
vehicle is detected ahead of you, your vehicle cruising
speed decreases within the range of about 40 km/h (25
mph) to about 135 km/h (85 mph). The display shows the
preset speed, the detected vehicle ahead and selected
vehicle-to-vehicle distance. If your vehicle gets closer to
the vehicle ahead because of insufficient automatic
deceleration, then the alarm warns you to also manually
apply brakes.
3 Follow-up cruising function: After deceleration, your
vehicle cruising speed changes in proportion to the speed
of the vehicle ahead to maintain an appropriate distance
from your vehicle to the vehicle ahead.
vehicle-to-vehicle distance can be changed. For details,
see "(h) Changing vehicle-to-vehicle distance" on page
475.
468
4 Acceleration cruising function: If the vehicle ahead
changes lanes, your vehicle cruising speed will be
gradually increased up to the preset speed, and your
vehicle resumes fixed-speed cruising.
This system operates by detecting primarily the reflectors
of the vehicle ahead. The distance may not be accurately
or absolutely detected in the following cases:
D The vehicle ahead has higher ground clearance, which
means that the placement of the reflectors is in a higher
position.
D The rear section of the vehicle ahead is extremely dirty.
D The vehicle ahead or other vehicles around you are
The flinging up water or snow.
D Excessive exhaust gas (black smoke) is coming from
the vehicle ahead or other vehicles around you,
obscuring your front view.
D There is an obstruction (protective film, sticker, etc.) on
the reflectors on the vehicle ahead, or reflectors are not
installed on the vehicle ahead or are damaged.
D Heavy luggage in the luggage compartment or rear
seats is causing the nose of your vehicle to tilt up.