empleinair- I think he means the option to control the hot to cold air ratio coming from the vents. Before iDrive there used to be a vertical knob above the vents that allowed for a quick adjustment of that ratio, now you have to do it through idrive.

That is not the same as controlling AC or heat however, you don't need idrive for that, but to do some micro adjustments to the airflow you will need to do it through idrive now.

I hope that makes sense..