Well the Adaptive part is only if your behind another vehicle. The Cruise control, I'm not sure.So does Adaptive Cruise Control.
My C-Max has Cruise Control, Hill descent control, and a L. Never used the cruise on down hill mountains because they are usually too windy to safely be on cruise anyway. Hill descent tries its best but doesn't blend in friction brakes. Low, seems more like a lower gear although the C-Max doesn't have gears. It will use engine braking though. I think hill descent will use engine braking too if the battery is full and can't regen anymore. It's been a while since I used it.