Also make sure that the vent behind the driver's seat is not covered up. We get temps in the 90s-100s and I never had gas mileage that low.
This is the right link: "Amazon.com: K&N VF2000 Cabin Air Filter: Automotive" it is really easy to replace, just need to pop off the glove compartment plastic
^Is that the one that you reuse in your C? Nevermind, I see that it's the same aforementioned brand name. That would pay for itself pretty quickly depending on your environment.
I haven't replaced one in C yet. But this is the right number. We have similar K&N in Gen3 - got tired replacing them every 20K. K&N holds a lot more dirt before it gets clogged so it doesn't need to be serviced as often
