Lexus LS460 2011 Owner's Manual page 267

Driving in vehicle-to-vehicle distance control mode
This mode employs a radar sensor and camera sensor to detect the
presence of vehicles up to approximately 120 m (400 ft.) ahead,
determines the current vehicle-to-vehicle following distance, and
operates to maintain a suitable following distance from the vehicle
ahead.
Note that vehicle-to-vehicle distance will close in when traveling on
long downhill slopes.
Example of constant speed cruising
When there are no vehicles ahead
The vehicle travels at the speed set by the driver. The desired vehicle-
to-vehicle distance can also be set by operating the vehicle-to-vehicle
distance control.
LS460_EE
2-4. Using other driving systems
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