[ImperialCrown]

Generally the newer high/premium line ATC-line vehicles have a particulate air filter. If they don't, one can be added.
Yours should be under the cowl screen in the engine compartment under a panel. I've given up saying which cars have one and which cars don't because I am proved wrong too many times.
My mom's bare bones Caliber didn't have one, but the door and slot was there for it, so I added one.

 

[moparroy]

Thanks - I am just as happy not to have one - for me its a bit of a gimmic - although it might keep leaves out of the heater fan which has happened to me but other than that I don't feel its required.
I should clarify - the plastic cowl screen has the door and slot for the filter same as the Charger - but under the door it looks nothing like the Charger. The filter is real obvious / easy to find in the Charger.
The Challenger is on the hoist for the winter now so I'll have another look in the spring when it comes back down.

 

[Dave Z]

Believe me, they're nice to have. We have it underneath the cowl.

I was very happy when every automaker started putting screens into their cowls. It was such a "duh!" thing to do. I took our '94-production Neon and glued a screen to the bottom of the plastic cowl and it stopped some of the fan noise -- leaves always got into the vents and it would click-click-click maddeningly. Also, of course, whenever we started hte car in the fall, we'd be hit with bits of leaves.

With all the dust and pollen and crap in the air from all the landscapers -- (we'd crack down on illegal immigration, but then who would blow our lawns with giant gas-powered reverse-vacuums every three days?) -- these things are really a good idea, if you live in the 'burbs.

As for why teenagers don't mow lawns, maybe one reason is because now homeowners demand a team of Mexicans with blowers, doing the edging twice a week and making sure there's nary a hint of a leaf or other stray organic matter on their lawns.

 

[JTE]

Since all of the air coming from the vents passes through the heater core and a/c evaporator, the filter is the only line of defense if you want to keep organic debris (dust) from clogging your causing poor performance and stink.

I see it as component protection not as an air freshener.

 

[ImperialCrown]

Febreeze markets a CAF and there are HEPA-certified ones for people with pulmonary disease/distress.
I agree that it probably will increase the lifespan of A/C evaporators and heater cores.