2012 Lexus IS 350 User Guide - Page 197

2-4. Using other driving systems Driving in vehicle-to-vehicle distance control mode This mode employs a radar sensor to detect the presence of vehicles up to approximately 400 ft. (120 m) ahead, determines the current vehicleto-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. Example of deceleration cruising When the vehicle ahead is driving slower than the set speed When a vehicle is detected running ahead of you, 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. 204