I think in short, the recirc would be used as follows:

1) If the car is sitting outside in the sun, the interior is 120, and it's 90 outside, you should let all the hot air out of the car, and when it's down to ambient temp of say 90 degrees, then you should use the recirc. The reason is, it's taking the same air and cooling it down from 90 to say 80, to 70, to 60 degrees, as opposed to taking it from the outside and cooling from 90 to 80, from 90 to 80, from 90 to 80.

2) If driving past bulldozers stirring up a lot of dust or something, where you get to avoid having at least some of that dust in the car cabin.

I'm just surprised they put a 20 minute max on that button. Any Jap car, you can have Max on all day.

1991 300d