Where Does the Odor in Old Cars Come From?

[DiJayce]

Old car odors come from the following sources: Residue smells: There are always various residues in the car, such as food crumbs, garbage, etc. If these things are left in the car and not cleaned in time, they will emit odors. Therefore, it's important not only to clean the car's interior regularly but also to prevent such residues from accumulating. Leather smell: The leather odor mainly comes from the interior. High temperatures and prolonged exposure to sunlight can cause the leather to age, resulting in unpleasant smells. In such cases, replacing the aged interior parts is advisable. Exhaust fumes: The presence of exhaust fumes inside the car is usually due to high levels of exhaust in the external environment, such as during traffic jams when many cars are idling, releasing a large amount of harmful substances. The best solution in such situations is to close the windows and switch the air conditioning to recirculation mode or turn it off to prevent exhaust fumes from entering the car.

[McEmersyn]

I've been driving a taxi for over 20 years and have seen too many old car odor issues. The most common one is the air conditioning evaporator. After prolonged use, condensed water accumulates in the pipes, which, mixed with dust, leads to mold and foul smells, especially the sour stench when the AC is first turned on in summer. The car carpet also easily harbors dirt and grime—spilled coffee or drinks that aren’t dried properly can mold, and snack crumbs that fall into seat crevices can rot and produce strange odors. Then there’s the aging rubber seals, which can leak during rain, soaking the floor and breeding bacteria. Even worse is the residual nicotine from a previous owner who smoked—it seeps into the ceiling fabric and lingers for years. To eliminate odors, thorough cleaning is essential. I use foam cleaner to clean the carpets and AC vents every month.

[SanJoanna]

My decade-old family car often has unpleasant odors, which I'm particularly concerned about when taking the kids out. The odors mainly come from three sources: First, the air conditioning system - dust accumulated on the filter mixes with humid air to create a musty smell, especially severe during seasonal transitions. Second, the trunk mat - I once discovered that sports shoes left for half a year made the entire trunk smell like sweat. Additionally, there are food residues trapped between seat layers - cookie crumbs dropped by kids mold in the crevices, producing a smell like spoiled bread. The aging leather seats emit a pungent glue-like odor that worsens in hot weather. Now I regularly use antibacterial spray on the sealing rubber strips, which helps block external odors from entering the cabin.

[MacAmir]

As a frequent visitor to auto repair shops, I've seen many old car interiors dismantled. The most common source of odors is mold patches in the AC ducts, especially the black, foul-smelling areas near the blower. Next is moldy floorboards, where water seeps into the carpet layers during car washes and doesn't dry properly, leaving a damp rag smell. Then there's the chemical odor released by dashboard plastic parts under intense sun exposure, which can cause dizziness. Smokers' car headliners absorb tar, creating stubborn smoke smells. I recommend changing the AC filter annually and using an ozone generator for deep sterilization, which shows the most noticeable results.