Originally Posted by NoHyperbole

I think the 2009 370Zs are not equipped with cabin air filters from the factory, but I believe you can install one anyway.

Here are two options:

OEM:
27277 1EA0B (7.875" W X 8.5" L X .75" H)

Aftermarket - ATP:
RA 141 (7.875" W X 8.5" L X .75" H)

People have used other brands and sizes, but the ATP RA 141 is an exact match for the OEM size.