Manual says Auto Recirculate will "Automatically switch between the recirculation and fresh air modes most suitable to environmental conditions." So if the car in front of you is emitting bad exhaust fumes or if there are bad smells in the area, will the mode automatically go to recirculate? Or does the auto function only work to better temperature, frost, or window fog? The manual does not seem to cover this.

 

The car's not going to know when something smells bad. :-) There's a button to go to recirculation manually when you know you're driving through an area of unusual conditions.

I'm sure there's a voice command, too.

 

Not sure but I know on my old TSX, when the temperature outside was ~100 degrees and I turned the air up high to cool down the interior, it would automatically switch to recirculate interior air. Then, after the cabin temp drops, it would switch back to letting in fresh air. This might be what they are referring to.

 

Pretty sure the "environmental conditions" referred to are the ones within the car. Auto-recirculate will be used when there is a large differential between the temp the operator sets and the ambient temperate in the car. I don't know what the large differential is but this is the way it works on most cars inclusive of out thee Acuras, all of our Hondas and Lexus.

 

Yep, my experience is that it is completely temperature and humidity related.

My Lexus Ls460 had what it called a smog sensor and a pollen filter. It actually sensed odors and either filtered them or switched to recirculate.

One of the most striking examples was cattle feed lots on I-40 west of Amarillo, TX. If you don't know they're there, and you don't have this system, you will suddenly be gagging. But with the LS40 I could motor right by and smell virtually nothing.

In the RLX last week, suffice to say I smelled the feed lots.

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The RLX does have an air quality sensor, but maybe its not 'sniffing' for the same things? I believe it's supposed to detect carbon monoxide from exhausts ahead and switch to recirc.

 

That is my understanding as well=it is Air Quality AND Humidity sensor

 

Similar situation in my rural home town, which is why I knew that it didn't filter out smells. :-)