The smell of mold can easily develop in cars if fungi and bacteria get in and stay around long enough. As these fungi and bacteria grow, an unpleasant odor emerges. You should try to fix the problem as soon as you start noticing this smell in your car.
Steps
Method 1 of 4: locate the source of the bad smell

Step 1. Inspect the interior of the car
Check everywhere, even in places out of sight, such as under carpets and under seats. Look for traces of excessive moisture or mold.
Run your hands in places where you have no visibility

Step 2. Examine the trim on the front and rear seats
Make sure they are free from mildew to the touch.
- Let the car dry in the sun with the windows down.
- Brush away any mold that is loosening from the trim.

Step 3. Inspect the air conditioning
When the air conditioning is on, the water condenses and attracts dust, spores, pollen and germs. This promotes the development of fungus and a moldy smell that you can deal with.
- Use an air freshener spray to treat your car's air conditioning every year.
- Spray deodorant into the air conditioning ducts to eliminate odors caused by standing water, bacteria and mold.
Method 2 of 4: Remove mold from the interior of your car

Step 1. Use a shop vacuum to vacuum up the mold
If you don't have such a vacuum, you can rent one from most hardware stores. These devices are excellent for removing mold from the heart of fabrics.

Step 2. Absorb mold with anhydrous calcium chloride
This product is sold in the form of absorbent granules. These can absorb twice their weight in water and liquefy as they absorb mold. To properly use anhydrous calcium chloride, there are certain steps that must be taken.
- Place the granules in a waxed and perforated cardboard container.
- Place the container in an enamel saucepan to collect the liquid that will drip from the first cardboard container.
- Leave the pan in your car until only liquid remains in the container, then fill it again with granules.

Step 3. Leave the windows open to exhaust the air
This is a handy tip when there is too much mold in the car. The sun will heat up the interior of the car and will help dry out any remaining mold on the seats, floors, etc.
Method 3 of 4: Neutralize the smell and deodorize the car

Step 1. Spray deodorant on problem areas
Spray several times on each area and let it penetrate in the places where the smell of mold comes from. This will help remove the odor from your car.
Don't put too much air freshener in your car. If you saturate an area, blot it to dry it

Step 2. Sprinkle with baking soda
Put some on the mold inside the car. Let it penetrate into the carpets. Wait about two hours before vacuuming up the excess baking soda with a hand vacuum or shop vacuum.

Step 3. Clean the floor and carpets
You can use laundry detergent on your car's floor and upholstery without any problem to remove stains, mold and anything else that causes bad odors.
- Remove any accumulated dirt or substances with a knife or spatula.
- Mix two tablespoons of lye with 250 ml of water in a spray bottle to moisten the affected area.
- After letting the cleaning solution sit for a few minutes, start blotting the area using a white glove.
- Vacuum the remaining mold with a shop vacuum.

Step 4. Go to a professional garage
Check the extent of the damage. If mold has passed through the foam on the seats, you will need to have them cleaned by a professional who employs the fumigation technique.
Call nearby garages for pricing. This service can be expensive
Method 4 of 4: Prevent the return of the musty smell

Step 1. The interior of your car should be kept clean
Food scraps and garbage that fall into your car provide a favorable environment for mold to grow. Vacuum your car and shake the floor mats regularly to effectively prevent the growth of fungus.

Step 2. The interior of your car should be kept dry
The mold feeds the fungi causing the smell of rot. It is important that the atmosphere in the car remains dry.
- Wipe up anything spilled immediately.
- Remove wet floor mats and allow them to dry before putting them back in the car.
- Leave the windows open to completely renew the air in your vehicle.

Step 3. Carpets and rugs should be kept dry
If your car is flooded or if you spill a lot of fluid and your carpet is saturated with it, fix the problem immediately to prevent mold growth. Carpet should be cleaned, deodorized and dried completely.
If the air is too saturated, consider bringing in a cleaning professional

Step 4. Improve the air quality in your car
The musty smell will come back if the air quality is poor. It is important to control mold with adequate ventilation to ensure that contaminated air is exhausted.
- Roll down your car windows regularly to let in fresh air.
- Maintain your air conditioning throughout the year.