It's the Adaptive Cruise Control Option. I can use regular cruise control mode or use the ACC. I can set it for 1,2,3 or 4 car lengths and when it senses I am getting to close to a vehicle it will slow down the vehicle until the vehicle in front of me is far enough away for the ACC to bring me up to the speed I had set. Sometimes it's nice when driving on the highway as long as there is not a whole lot of other vehicles around. In a "rush hour" traffic scenario, not so much. It's not available with a manual transmission for obvious reasons. My SXT was fully loaded except for the Blacktop package, but I swapped out the chrome etched grill and chrome fuel door for the blacktop edition ones plus added the Scat Pack spoiler. My next thing to add is the factory T/A ram air hood and ram air intake package. I'm going to have the hood painted the same color as the rest of the car. I don't like the whole matte black hood look.