Car smells guide: what your car odours might be and how to deal with them

Cars come in all shapes and sizes, and make all kinds of unique and sometimes wonderful noises. But they also produce different smells, and if your car has started developing a new odour, it’s useful to know what might be causing it, and what course of action to take to fix it.

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These car smells range from simple everyday odours to ones that could indicate some kind of new problem with your car. Unfortunately, there’s still no satisfactory technology that allows you to smell our guides here on Carbuyer, but hopefully after reading the following guide, your nose should have a better idea of what to sniff out for next time you go for a drive.

My car is making an unfamiliar smell, what should I do?

This depends on what smell your car is making. Some, such as the ‘new car smell’, might persist for years, but smells like this are clearly less of a concern than a burning smell, which could require immediate action on your part to avoid a dangerous situation.

The best case of action with any new odour however is to pin down what’s causing it, investigate where it’s coming from, and then deal with it appropriately – just as you would if something in your house began to smell.
 

Some common car odours explained

Below we’ve described in detail some of the smells you might experience in a car. These have varying levels of severity, from simply being a nuisance to ones that might require immediate attention, with the ones at the top of the list being less serious than those towards the bottom.

We’ve also explained what you should do to counter, avoid, or remove each odour. Some are simple enough to fix yourself or through changes in driving style and behaviour, while others may need the attention of a professional mechanic.

1. Synthetic and plastic smells

These are among the least serious odours you’re likely to experience in a car, and are typically down to the composition of the materials from which the cabin is constructed. Many of us are familiar with that ‘new car smell’, which is down to exactly this – the new plastics (plus other materials such as fabrics and leather) create an aroma that’s more noticeable when a car is new but tend to fade over time. It’s more pleasant in some cars than others – a brand new leather and wood-lined Bentley will tend to smell better than a fifteen grand supermini!

The smell can be stronger even on older cars in warm weather as heat causes plastics to release compounds. There have been studies into the safety of some of these compounds, though they’ve so far been inconclusive.

What should I do? If you find the smell unpleasant, there are sprays and air fresheners that can mask it, while in warmer weather, driving with the windows down to introduce fresh air also helps.
 

2. Damp and mildew smells

There are a couple of reasons you might smell dampness in a car. In the wetter months, the most common reason is that moisture is somehow getting into the car and being allowed to sit. This might just be a result of leaving wet clothes in the boot (such as a jacket or wellies), but it may also be that water is getting in through an old or damaged door or window seal. In older cars and convertibles, this is even more likely, with far more places that water could potentially enter.

More mildew-like smells could be a sign of problems with your air conditioning system. Air-con works best if it’s regularly used, but if you’ve not touched it in months, moisture can sit around allowing bacteria to grow. When you do finally use it again, these smells are pushed into the cabin. If it happens only briefly when using the air-con for the first time in a while, it’s nothing to worry about, but persistent odours may need attention.

What should I do? For dampness, solutions range from the simple to the slightly trickier and more expensive. Removing anything that might be wet is a good start – as well as floor mats, if you have somewhere at home to dry them – and a small dehumidifier can quickly absorb any residual moisture. But if your door or window seals have gone, or your convertible top is leaking, you might be in for a more expensive fix – likewise if your car is old and rusty and letting water in through every gap and hole.

For air conditioning smells, your best option is to go back to your dealership if the car is fairly new, or to an air conditioning specialist if your car is out of warranty. Both should be able to rectify the issue, at a cost.

3. Acrid smells

Acrid car smells tend to be a result of either your car’s brakes, tyres, or in a car with a manual gearbox, the clutch. Brake smells are probably the more common and typically a sign that the brakes are working hard for some reason – perhaps you’ve been driving downhill for a while and have used them a lot, or if a whole motorway has just come to a halt and you’ve had to do an emergency stop from high speed, you may notice an odour from your brakes there too. The smell is actually most obvious if you’ve ever followed a lorry down a hill, as those really do use their brakes hard.

Tyre smells are relatively uncommon, unless you’re a particularly enthusiastic driver who tends to get their tyres very warm – or likes to spin them up and create a smokescreen. However, you may also smell an acrid, rubber-burning smell if one of your tyres is failing, and either about to burst or has fully deflated.

Clutch smells are less common, and result from the clutch ‘slipping’. The clutch is a friction-based device designed to transfer power from the engine to the gearbox, and when it slips, it’s not doing this as effectively, and releases a smell from the friction material burning off.

What should I do? If you can smell your brakes, this isn’t necessarily cause for alarm – especially if you’ve only been smelling the brakes of the vehicle in front. However, it’s probably a sign you should go a bit easier on them for a while – if you’re going downhill for instance, try changing to a lower gear and using engine braking, rather than constantly pushing the pedal. Keep working them hard and their performance might start to decrease; the next sign will be your brake pedal starting to feel softer and spongy, and needing a harder press to slow you down. There’s also a chance a faulty brake caliper is pushing one of the pads in constant contact with a disc, in which case it’s time to take your car to a mechanic.

Tyre smells from enthusiastic driving are probably a sign you should take it to a racetrack, but if you’re getting them just driving down the road, then pull over somewhere safe, as your tyre might be about to fail, or may already have deflated. Either way, it’s time to fit your spare (if you have one), or get on the phone to your breakdown provider.

If you’re getting the even more acrid odour of clutch, it may be on its last legs – though it could also be worth adapting your driving style. If you ‘ride’ the clutch – slipping it a lot between gears, or using it to hold you at traffic lights rather than applying the brakes or handbrake – you will wear it out a lot more quickly.
 

4. Hot and sweet smells

A warm, sweet odour emanating from your car while it’s running is typically related to the car’s cooling system. The purpose of the cooling system is to cool down the engine, pumping a mixture of water and coolant through your engine (the latter sometimes called anti-freeze, as it also prevents your cooling system from freezing when the mercury drops) and dissipating it via the radiator.

If there’s a problem with the cooling system though, you might begin to smell this coolant/anti-freeze, which has quite a sweet smell. This might be caused by a leak, but in more serious cases it can be caused by your car overheating due to a failure. In theory, a dial or warning light on the dashboard should have warned you of problems well before this point, but in older cars you may be at the mercy of your sense of smell.

What should I do? If there’s any problem with your cooling system on the road, you should stop your car somewhere safe and turn it off, before your car overheats and causes real damage. The sooner you identify cooling issues, the sooner you can get them fixed, avoiding bigger bills down the road.

5. Oil smells

This one is probably a little self-explanatory, but essentially, all engines use oil – either mineral, semi-synthetic, or synthetic – to lubricate the moving parts inside your engine, while components like your gearbox and differential use different (typically much thicker) oils for their own lubrication.

If you can smell oil, then it’s probably leaking from somewhere, particularly noticeable when the car has been used and then parked up again – oil gets thinner when it’s hot, which means it can leak more easily, while the warmth of your engine can make these odours easier to smell.

What should I do? Naturally, you should get any oil leak investigated by a professional. Your engine and other components need oil to operate and a leak means constant topping-up to keep these fluids at an appropriate level, which will cost you money. But it’s also an environmental issue, and potentially a safety issue for yourself and other road users – dropping slippery fluids onto a road is a recipe for disaster. In extreme cases, an oil leak can become a fire risk too, so it’s best to get this looked at.

6. Petrol and diesel smells

Like being able to smell oil, petrol and diesel smells are somewhat self-explanatory. If you’re nowhere near a fuel station but can smell that distinct fuel smell, then your car probably has a fuel leak from somewhere – the exception being on much older petrol cars with carburettors, which tended to smell much more strongly of petrol fumes.

There are other odours associated with petrol and diesel too though, potentially caused by running issues. A strong smell of unburned fuel from a petrol can indicate it’s running ‘rich’ and needs maintenance.

Some diesels emit a sweet smell when first started up, most noticeable in cold weather, which is typically a byproduct of emissions equipment such as the catalytic converter and diesel exhaust fluid (DEF). Stronger diesel and sooty smells (a bit like a train station!) suggest slightly rich running, but are more common on older, pre emissions-equipment diesels (or those which have had particulate filters and other equipment illegally removed).

What should I do? Pure fuel smells need immediate attention as they could indicate a leak – and with petrol vapour in particular being very volatile, any leak is a real safety issue.

Smells from the exhaust vary from needing no attention at all, to having your car serviced to correct them. Rich running in petrols and diesels may cause engine issues further down the line, but it also means you’re probably wasting fuel, and this means higher fuel bills. And if you’ve just bought a relatively recent diesel vehicle and it’s unusually pungent, you might want to check that the previous owner hasn’t had particulate filters and other emissions equipment removed. Not only is it illegal, it’s also damaging to the environment.
 

7. Burning smells

It goes without saying but you really do not want to smell burning from your car, and there’s almost no instance where smelling something burning is a good thing. In the best case scenario, it might be that something like an incandescent bulb has fizzled out, but in the worst case, you might find yourself standing a hundred feet away from your car ten minutes later watching it burn to the ground.

The most common burning smells are electrical, and while not something you want, you should be able to identify it as such fairly quickly as the insulation around wires and cables tends to emit a particularly acrid pong. Given how many systems in a modern car are electrical, this may cause noticeable issues elsewhere, even if it doesn’t turn into an actual fire.

You may smell burning, and even see wisps of smoke, from your brake pads – a result of either repeated heavy braking or a caliper and pad sticking and causing excess friction. This is potentially among the less serious burning smells, as brakes and the area around them are designed for high levels of heat, but you’ll probably want to park up for a while and let them cool off.

What should I do? If you smell burning and see actual smoke from anywhere within your car or from around the engine compartment, immediately pull over in the safest spot you can manage at short notice, get out, get any passengers out, and get far away from your vehicle. The main goal here is your safety, and whatever happens to the car is secondary.

If you smell smoke at all though, it’s probably a good idea to stop safely somewhere, turn off the car, and have a look around, under the bonnet and in the fuse box – though only if the smell shows no signs of escalating.

If you’re confident and know your way around your car, it may be worth carrying a small extinguisher in your glovebox or a door pocket. It won’t put out a raging inferno, but if used correctly, may stop small fires developing into something much bigger.

More on car problems

• Causes of an engine management light
• Complete guide to dashboard warning lights
• Reporting a fault on a new car
• Guide to car recalls
• What does smoke from my exhaust mean?
• Car engine noise explained
• Car suspension noise: what does it mean?
• Car windscreen repairs and replacements
• What to do about a noisy car exhaust