How do you get rid of a mildew smell in a car?

You can put charcoal briquettes or a box of baking in the closed area after you're done to absorb any other smell that will arise in the future. Installing a dehumidifier or an electric air vent fan will discourage moisture from collecting in that area and encourage the air to move around. As a final touch, use an air freshener spray or Fabreeze to bring back a fresh smell in to the closed area that previously smelled like mildew.