Cars don't just diagnose dangerous things. They can also use their sensors to make your life easier and more pleasant. Without you, who would your automotive robot overlord lord over? It's in the car's best interest to keep you happy.
Take, for example, the Acura RLX, which senses the humidity level in the cabin. If the interior gets too damp, it will turn on the air conditioning and recirculate the air to prevent fog or frost from collecting on the windows.
Now, if the humidity is of a more "steamy" nature, wink wink, the cold blast of air the car sends out of the vents is due to a fit of jealousy. Guaranteed.