Lexus RX 450h 2010 Owner's Manual page 229

2-4. Using other driving systems
Driving in vehicle-to-vehicle distance control mode
This mode employs a sensor to detect the presence of vehicles up to
approximately 400 ft. (120 m) ahead and to judge the distance between
your vehicle and the vehicle ahead of you.
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-vehi-
cle distance can also be set by operating the vehicle-to-vehicle distance con-
trol.
Example of deceleration cruising
When the vehicle ahead is driving slower than the set speed
When a vehicle is detected running ahead of you in the same lane, the system
automatically decelerates your vehicle. When a greater reduction in vehicle
speed is necessary, the system applies the brakes. A warning tone warns you
when the system cannot decelerate sufficiently to prevent your vehicle from
closing in on the vehicle ahead.
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