Moisture inside the cabin brought about by humidity and wet weather is a catalyst for mold growth. Not only do mold spots look hideous (especially on dark-colored interior trim), but they can also be hazardous to your health when the spores are inhaled. These nasty marks can easily be avoided or removed, so here are some easy pointers to tackle this issue.
To keep the atmosphere inside your car dry, you can use dehumidifiers (look for the ones with activated charcoal) or large desiccant bags that you can stow under the seats. Charcoal for grilling is also good and cheap, but it could be difficult to find nowadays.
To clean or remove mold, you can use interior-detailing sprays found at many automotive supply stores. Better if the product is pH-neutral so your vehicle’s delicate bits won’t react or fade. Spray the interior detailer on a soft terry towel and clean the affected surfaces gently. If you’re really on a tight budget, diluting one or two drops of dishwashing liquid in 500mL of distilled water is also a good cleaning solution. Never use chlorine or strong bleach for your interior trim.
Sometimes, your air-conditioning system (especially if your vehicle is old) can be the culprit for mold formation. Having it serviced and cleaned once a year is ideal. You can also use anti-odor, antimicrobial air-conditioner aerosol-spray treatment such as Sonax Car A/C Cleaner, Turtle Wax Power Out Odor-X, or Ma-Fra Odorbact Out. These products can be purchased online or from your favorite auto supply store, are very easy to use, and will keep the funk out of your cabin and air-conditioning.
To help keep the system dry especially in rainy weather, run your A/C at its warmest temperature setting with the blower on high for a few minutes when you arrive at home to evaporate any moisture remaining within the vent channels.
Avoid keeping damp or wet items such as rags, umbrellas or fabric floor mats inside your vehicle. Furthermore, never leave any kind of organic waste such as food items in your car. Since textile/fabric floor mats retain water, use rubber floor mats for the wet season. Dish-type rubber mats are great as they trap water and prevent it from soaking up your carpet, which will promote bacteria and mold formation.
For those of you with a little extra cash to spend, a proper professional interior-detailing job would be great. Some methods usually employed include steam/foam cleaning and the application of interior ceramic coating with nanotechnology that prevents microbes and mold from forming on or clinging to your cabin’s surfaces while providing stain and moisture protection. This should provide long-term benefits, but it will also depend on how you care for your vehicle overall.