2004 Cadillac XLR Owner's Manual - Page 132

Other Vehicle Lane Changes Using ACC on Hills If another vehicle enters the same lane as you, ACC will not detect the vehicle until it is completely in the lane. Be ready to take action and apply the brakes yourself. How well ACC will work on hills depends on your speed, vehicle load, traffic conditions and the steepness of the hills. ACC may not detect a vehicle in your lane while driving on hills. When going up steep hills, you may want to use the accelerator pedal to maintain your speed. When going downhill, you may have to brake to keep your speed down. Applying the brake disengages ACC. Many drivers find this to be too much trouble and don't use ACC on steep hills. 3-22