My car is an Audi S5 which has the normal cruise control (non-adaptive) with auto braking (applies brakes when going downhill too fast).
For some reason when engine braking the car uses around 4L/100KM instantaneous petrol. If I disengage cruise control, it will use 0L/100KM as it shuts off fuel. Therefore, I prefer to turn off cruise control sometimes when going down long roads.
Is cruise control just an electronic software, or are there mechanical / mechatronic devices which get engaged/disengaged when you turn CC on/off? Is there any harm in turning CC on/off a lot of times?