How to Eliminate Musty Smells From a Car Cover
⚡ Quick Answer
A musty car cover smells that way because trapped moisture let mildew grow in the fabric. Wash it in a large-capacity machine with mild detergent, dry it fully in the sun or with airflow, then store it in a breathable bag in a dry spot. Skip the fabric softener.
How to fix a musty car cover
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1
Wash with mild detergent in cold or warm water -
2
Air-dry completely before folding it -
3
Store it loose in a breathable bag, not sealed plastic
Mistakes that bring the smell right back
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Folding it while even slightly damp -
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Sealing it in a plastic storage bag -
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Using fabric softener, which traps moisture
You pull the cover off your car and that smell hits you first. Damp, sour, a little like wet cardboard left in a closet too long. Daniel Brooks here, and I’ve pulled this exact smell out of more covers than I can count. It’s not your car that’s the problem. It’s moisture trapped in the fabric, and it has a fix.
The good news? A musty car cover almost never needs replacing. It needs a proper wash and a dry-out routine that actually works.
Here’s exactly how to get rid of it, and how to keep it from coming back every time you store the cover.
📌 Key Takeaways
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Trapped moisture is the real cause, not dirt or age. -
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Home washers with a center agitator can damage cover fabric — use a laundromat’s commercial washer instead. -
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Full drying matters more than the wash itself for stopping mildew. -
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Breathable storage bags stop the smell from returning between uses.
Why Does a Car Cover Smell Musty?
A musty car cover means moisture got trapped in the fabric and mildew started growing there. Mildew thrives anywhere damp and dark, and a folded car cover is exactly that. So if you’ve ever balled up a wet cover and shoved it in its bag, that’s almost always the cause.
Here’s the thing. Car covers absorb rain, dew, and condensation by design — that’s how they protect your paint. But if the cover goes back into storage before it dries, the moisture has nowhere to go.
📋 Common Causes of Musty Car Covers
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Folding it damp: The number one cause. Even slight dampness lets mildew take hold within days. -
Sealed plastic storage: Airtight bags trap any leftover moisture against the fabric. -
Long stretches without washing: Pollen, dirt, and bird droppings hold moisture and feed mildew growth over time.
According to EPA’s guidance on mold and moisture control, mold and mildew need only a damp surface and time to take hold — there’s no way around drying the source out completely. So that’s the goal with your cover: get it dry, and keep it dry.
How Do You Wash a Musty Car Cover?
Wash a musty car cover with mild detergent in a large-capacity commercial washer, never a home machine with a center agitator. The agitator can snag and tear cover fabric, so a laundromat or a hose-and-bucket hand wash works far better.
🔢 Step-by-Step: Washing Out the Musty Smell
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1
Check the care tag first
Fabrics vary, so confirm it’s machine washable before you start.
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2
Use a commercial washer
Laundromat machines skip the center agitator that can rip cover fabric.
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3
Add mild detergent, cold water
Select the delicate cycle. Skip bleach and harsh detergents that break down coatings.
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✓
Rinse a second time
An extra rinse clears leftover detergent that can attract dirt and hold odor.
⚠️ Warning
Skip fabric softener and dryer sheets. They leave a residue that traps moisture in the fibers, which feeds the exact mildew you’re trying to remove.
If the cover has stubborn bird droppings or sap, treat those spots before the main wash. A little vinegar mixed into the detergent solution loosens dried-on stains so the wash cycle can finish the job.
How Long Does a Car Cover Need to Dry?
A car cover needs to dry completely before storage, which usually takes several hours of direct sun or a full day of indoor airflow. Drying time matters more than the wash itself, since any leftover dampness restarts the mildew cycle within days.
100%
dryness required before folding
2-3
days max for mildew to take hold in damp fabric
Here’s a quick way to choose the right drying method for your situation.
Never use a clothes dryer. Heat can warp the elastic hems and waterproof coating that keep the cover working.
Check the underside, seams, and elastic edges before you call it dry. Those spots hold moisture longest and they’re where mildew starts first.
How to Store a Car Cover So It Stays Fresh
Store a clean, fully dry car cover loosely in a breathable bag, kept somewhere dry like a garage shelf or closet. Avoid sealed plastic bins and damp basements, since both trap residual humidity against the fabric even after a thorough wash.
✓ Storage Checklist
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Cover is completely dry, including seams and elastic edges -
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Stored in a breathable bag, not sealed plastic -
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Kept in a dry spot, away from basement humidity
If you store the cover somewhere naturally humid, like a garage near a washing machine, a moisture absorber in the storage bag adds an extra layer of protection.
Recommended Product
DampRid Refillable Moisture Absorber, 11 oz., 6-Pack, Fresh Scent
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A cup of this tucked into the storage bag pulls excess humidity out of the air around the cover, which keeps mildew from starting back up between uses.
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What Most People Get Wrong About Musty Car Covers
Most people think a musty cover means it’s worn out and needs replacing. That’s rarely true. So if you’ve been eyeing a new cover, try a proper wash and dry cycle first.
A second mistake: spraying air freshener directly on the smell instead of washing it out. That only masks the odor for a day or two, since the mildew causing it is still alive in the fibers underneath.
A third one — people assume any home washing machine works fine. But here’s why that matters: a center-agitator machine can snag the fabric and tear seams, which leaves gaps that let in even more moisture next time.
How to Keep the Musty Smell From Coming Back
📋 Prevention Habits That Actually Work
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Never cover a wet car: Wipe the car dry first, or the cover traps that moisture instantly. -
Pull it off after rain: Let both car and cover air out rather than leaving a wet cover on overnight. -
Wash it every few months: Regular washing keeps dirt and pollen from building up moisture-holding layers. -
Choose a breathable cover: Breathable fabric releases trapped moisture instead of sealing it against the paint.
Conclusion
A musty car cover is a moisture problem, not a defect. Wash it properly, dry it all the way, and store it where air can move around it. Right now, go check your stored cover for damp spots before you fold it away again — that two-minute check is what stops the smell before it starts.
Frequently Asked Questions
How do you wash a car cover?
Wash it in a commercial washer with mild detergent and cold water on a delicate cycle. Avoid home machines with a center agitator, since they can tear the fabric. Rinse twice to clear out all the detergent.
Can you put a car cover in the dryer?
No. Dryer heat can warp the elastic hems and damage the waterproof coating on most car covers. Air-dry it instead, either in the sun or with indoor airflow from a fan.
Does vinegar remove musty smell from a car cover?
Yes, as a stain pretreatment. Mix a small amount into your detergent solution before the main wash to loosen dried-on stains and odor-causing residue. It works best alongside a full wash and dry, not as a stand-alone fix.
Can I use fabric softener on a car cover?
No. Fabric softener leaves a residue on the fibers that holds moisture instead of releasing it. That residue actually makes mildew more likely to come back after washing.
How often should I wash my car cover?
Every two to three months for regular outdoor use, or sooner if it’s been exposed to heavy pollen, rain, or bird droppings. Frequent light washing prevents the buildup that traps moisture long-term.
What causes mold to grow on a car cover?
Mold grows when moisture sits in the fabric for an extended period, usually from folding the cover damp or storing it somewhere humid. Dirt and organic debris like pollen also feed mold growth once moisture is present.
When should I replace a musty car cover instead of cleaning it?
Replace it if mold stains remain after washing, or if the fabric has torn or lost its waterproof coating. A clean cover that still repels water and shows no visible mold stains is worth keeping.
Daniel Brooks is an automotive writer and product researcher focused on car accessories, car tech, maintenance, and practical driving guides. At Plug-in Car World, he helps drivers make smarter automotive decisions through honest reviews and research-driven content.