I recently changed mine and definitely no carbon layer (used to work in a factory that had these bad boys in the HVAC equipment, so I know what it looks like). I have read (but have not confirmed for myself) that the 1st gen Fits had carbon (or maybe I was just reading the BS claims of the aftermarketers), but to be honest, such a thin layer of carbon probably would not be too effective anyway.

 

I actually put an activated charcoal filter in for one of my changes.

They're selling for $20 now, but were $28 when I got one 2 years ago.
I didn't really notice any difference in air quality.