If you use air fresheners, it would be a way to do so without having the tacky shit hanging from your mirror or the cups of stuff under your seats. My girl had a car a while back that had a cabin filter. The smell of a certain dryer sheet (one of the Bounce scents?) was calming to her because it reminded her of her grandma's house. She would lay a dryer sheet over the cabin filter and reinstall it. It wasn't overpowering so you weren't hit with a wave of artificial scent every time you opened the car after being closed up for a while. Just a light, airy scent that was wafted only when the A/C was on, and with filtered, pollen-free air at that.
My Tahoe has no air fresheners and I'd like to keep it that way for as long as possible. It smells like what it is in there- lightly aged automotive leather, plastic and carpet. If it ever needs "help", I'll likely add the filter and dryer sheet of her choice.