I think that term auto setting stealing is accurate.
You set the temp at say 21C and it stays at that. Just like an office block.
So in winter the engine needs to run almost const to provide heat, and likewise in summer to power a/c.
It is more than just the extra load of the aircon, as in traffic the engine needs to run much more.
Eco mode ameliorates engine use by allowing for delta in actual - desired temps.
But manual use of fan means you get your initial blast of heat / chill, then you live with it being hotter or colder.
Most cars now have touch controls and so temp is set once and left.I
Turning can off or low is key for economy.
I am astonished at roman's blase comment of when above 30C. Our local tv done a feature when it hit 31C this summer.
my Focus needs heat on full blast on hot days to stop it overheating on hills.