I don't have the option. There have been in a few situations in which I would have appreciated ACC, but mostly I'm quite pleased to have avoided it. Like the rear TV's and Nightvision, I'm overall glad I didn't spend the cash on these features.
991.2 '17 Porsche 911 C4S (on order)
F10 '11 535i Titanium Silver on Oyster/Black (garage)
E46 '02 330i Steel Blue on Black (Gone but not forgotten!)