Originally Posted by maxcichon

'Dog beat me to it. It's most likely just the cabin air filter. They get very fuuuuunky after one year.

Buy a new one. Or two-for next year. They are very easy to find, even at chain carparts stores. They are available in charcoal-impregnated. Best choice for $2 more.

It's located above the passenger's feet in a rectangular box you can easily access. Slide the 2 clips over and pop the cover off.
Pull the funky filter out. DO NOT LOOK DIRECTLY AT IT! GROSS! Look at the way it's installed, as it's easy to forget and you're working upside down. It's a kinda' tight fit.
Put the new one in and replace the cover.

My Crossie is garaged, but it stinks pretty bad after a year. It's a Spring Cleaning item...

But, of course, the drains may be plugged. Make sure they work...