Your Trunk Space Could Be the Reason Your Car Smells So Bad: Look For These 5 Causes

May 16, 2025

car smells bad — Image Source: 123rf.com

Nothing ruins a car ride faster than a mystery stench. If you’ve cleaned your upholstery, tossed out old fast food bags, and still can’t figure it out, look behind you. Your trunk, often overlooked in cleaning routines, might be the culprit. From forgotten groceries to leaky spare tires, the cargo area can quietly collect some nasty surprises. If your car smells bad and you’re out of ideas, it’s time to pop the trunk and investigate. It could be one of these five things.

1. Forgotten Groceries and Spills

I’ve found spoiled items in my vehicle before. You might forget that you ordered that half gallon of milk from the store and leave it in your trunk after you pick up your order. I’ve done it with meat (which smells absolutely horrendous, especially if it’s summertime). The smell itself typically takes a couple of days to develop, maybe sooner if the weather is a factor. However, the stench will linger for weeks if you don’t notice it right away. So, if you notice a foul smell, check your trunk for forgotten items.

2. Damp or Moldy Carpeting

Moisture is your trunk’s worst enemy. Maybe you hauled wet beach towels, got caught in a rainstorm, or left your trunk ajar overnight. That trapped moisture seeps into the carpeting or the spare tire well, where it breeds mildew and mold. The result? A musty odor that slowly creeps into your car’s cabin. If your car smells bad in a way that reminds you of a locker room, mold in the trunk may be to blame.

3. Forgotten Gym Bags, Shoes, or Clothes

We’re all guilty of tossing stuff in the trunk and forgetting about it. But sweaty gear, dirty shoes, or damp clothes left too long can turn into a portable biohazard. As the days pass, the smell worsens and saturates the surrounding area. Even if the item dries out, the odor it leaves behind can persist in the carpet and upholstery. To keep your car from smelling bad, make sure your trunk isn’t doubling as a forgotten laundry hamper.

4. Chemical Spills or Cleaning Supplies

Maybe you keep motor oil, windshield washer fluid, or cleaning sprays in your trunk. That’s smart—until one of them leaks. Harsh chemicals can give off a strong, sometimes toxic smell that’s hard to ignore. Even a slowly leaking container can cause a persistent odor and damage your trunk lining. If your car smells bad and you’ve ruled out food and mildew, double-check for bottles that may have tipped or cracked.

5. A Faulty Trunk Seal Letting in Fumes

Sometimes the issue isn’t what’s in your trunk—it’s what’s getting in from outside. A worn-out or cracked trunk seal can let in exhaust fumes, road grime, or moisture. This can lead to a mix of chemical and damp odors, and even pose a health hazard over time. You might not notice anything wrong until the smell becomes impossible to ignore. If your car smells bad and no items are to blame, inspect the trunk seal for damage or deterioration.

That Stench Isn’t Just Gross—It’s Preventable

A smelly trunk may seem like a minor issue, but it can quickly turn your car into a place you dread being. Fortunately, once you find the source, most trunk-related odors are easy to fix and even easier to prevent. Clean out your trunk regularly, inspect for spills and dampness, and don’t treat it like a storage locker for your gym or grocery leftovers. If your car smells bad, it might just be trying to tell you to pay attention to what’s behind you.

Have you ever discovered a terrible smell in your trunk? What was the cause, and how did you fix it? Share your smelly car story in the comments!

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