Mildew is a disgusting and dangerous microscopic fungus that grows on damp surfaces. Washing your car and not properly drying the convertible top before letting the top down will cause mildew to form on the top. Mildew growth can discolour and damage the convertible top if left untreated. You could use a designated cleaner to remove the mildew, but there is a simple home remedy for ridding your car's convertible top of the fungus.
Sweep off with a broom or use a shop vac to remove any loose mildew from the convertible top. If sweeping with a broom, sweep gently. Wear rubber gloves.
Park your car in a garage or other covered area.
Sprinkle 1 tbsp of baking soda onto each mildew spot on the convertible top.
Let the baking soda sit overnight. The baking soda will help dry out the mildew.
Rinse the entire car with the water hose.
Apply 1 tsp of nonabrasive bathroom cleaner that contains mould-fighting agents to each mildew spot.
Let the cleaner sit for five minutes.
Scrub the cleaner into the mildew spots gently with a nonabrasive sponge. Rinse the mildew spots with water as you are scrubbing, to break the stain up and remove it.
Rinse the convertible top.
Wash the car, including the top, with a car wash and a clean soft rag or towel.
Rinse the car.
Dry the entire car with a clean chamois or microfiber towel. Make sure the convertible top is completely dry.
Whenever you are washing your car and the convertible top, make sure you wet the entire car first before applying a car wash or other cleaner. Do not spot-clean the convertible top--irregular shading or discolouration could occur. To keep mildew from forming on the convertible top, dry the top completely after each washing or after a rainfall before letting the top down.