If you do not own a shop vacuum, you can rent one from most home improvement stores. These machines work great to suck-up moisture that lies deep within fabrics. This product comes in white granules and works to absorb moisture. It can hold double its weight in water and liquefies as it absorbs moisture. Here is how to properly use anhydrous calcium chloride:  Put the granules in a waxed cardboard container that has perforated holes. Place the container in an enameled pot to collect the liquid that drips away from the container. Leave the pot in the automobile until only liquid is let in the container and then refill it. This is a helpful tip to consider when there is too much moisture for you to get rid of on your own. The heat from the sun will warm up the inside of the car and work to evaporate some of the moisture left behind on seats, the floor and anywhere the mold smell originates.
Use a shop vacuum to suck-up any moisture. Absorb the moisture with anhydrous calcium chloride. Leave the car windows open to let the car air out.