The interior of my MX-5 has got damp and mildewed a few times now. I have some success with putting a dehumidifier on the front seat for a couple of days.

The best way I have found though is to take it for a drive for a couple of hours, the heat soak through from the engine/gearbox does a good job of drying it out. Might not work quite as well on the Focus though (the MX-5 gearbox sits between the footwells).
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Remind me to change my signature to something more interesting someday