Car noise limits: UK laws and how to report noisy car exhausts or engines

Modern cars are remarkably quiet, and we don’t just mean electric cars. You might have found yourself surprised just how little noise the last new car you bought was, and even standing outside, right next to the bonnet or the exhaust pipe, you might not even hear your car running if the ambient noise isn’t already low.

The reason for this, beyond simply making cars more refined to the benefit of those who drive them, is that external car noise limits are tightly regulated by law, to prevent traffic noise becoming too much of a nuisance.

In the UK, this legislation amazingly started all the way back in 1929, but the limit has steadily been reduced over the years, and it means that at anything other than very low speeds, combustion-powered vehicles are often no louder than electric ones from outside the car, since tyre noise quickly takes over as the largest source of sound as speeds increase.

You might also wonder, then, why some cars seem to be very loud indeed, and if a local vehicle is disturbingly loud, what you might be able to do about it. The laws governing car noise are clear and it is possible to report cars making excessive noise from their engines or exhausts. Read on to find out more.

What is the current UK car noise limit?

The first ‘Motor Cars (Excessive Noise)’ regulations were introduced back in 1929, and limits have been progressively reduced since then. In 1978, for instance, vehicles were allowed to produce 82 decibels in “normal traffic conditions”, which generally involves a drive-by test measured from a fixed point 7.5 metres away, under a certain level of acceleration.

Since 2016 the UK adopted EU regulation 2014/540, which set an initial noise limit of 72 decibels – actually around ten times quieter than the 1978 limit, since decibels use a logarithmic scale – and this will go down to around 68 decibels by 2026, alongside revisions to the car noise test procedure to make it more accurate.

Incidentally, legislation states that ‘off-road vehicles’ are allowed to be one decibel louder, and wheelchair accessible vehicles and armoured vehicles 2dB louder – accounting for the fact these tend to require modifications to the base vehicle.

UK car noise limits

Unsurprisingly the legislation is aimed at vehicles in their factory state – a complex set of rules, since cars are incredibly varied in their size and performance, have different engine types, use different fuel types, and are sold at different price points. In other words, the legislation recognises that a cheap, less advanced car and an expensive luxury model designed to be quiet both need to be capable of meeting these conditions.

It’s also led to a lot of the technology you see in modern cars, and why they function in a particular way. A performance car might make a lot of noise on start-up for instance, or under hard acceleration, but it will often be configured so that during the kind of acceleration under which cars are tested for noise, its exhaust valves close and it shuffles up gears early to keep noise to a minimum.

If that seems a little sneaky, then it at least keeps cars largely quiet in urban environments for example, where noise disturbance can have the most impact.

Modified cars and noise limits

Despite the noise limits, we’ve all heard vehicles driving around that are clearly far louder than this, and typically that’s because they’ve been modified with aftermarket equipment. This isn’t illegal in itself, provided the parts are legal in the country in which they’re being used (Germany has strict regulations for modification, for example), but it is definitely a grey area, since the UK’s Vehicle Certification Agency expressly notes that “it is illegal to modify the exhaust system of a vehicle to make it noisier than the level recorded for that model at type approval”.

In theory, you can modify a car’s exhaust system in a way that keeps it within these regulations, or even drive in such a way that does, but clearly, the line here is quite slim, and it isn’t uncommon to hear cars that are very loud. If a car is also making loud pops and bangs, there’s a chance emissions equipment has been changed or removed, which is also illegal.

The DVSA (Driver and Vehicle Standards Agency) recently brought a successful prosecution against a company that was advertising and fitting illegal car exhaust modifications in the UK. 

Is car noise a factor in the MoT test? 

Even modified cars have to pass an MoT test every year once they’re three years old but the rules around car noise and the MoT test do create a grey area. 

The MoT inspection manual has ‘Nuisance’ as a category in section 8 and under this the requirements for noise, emissions, leaks and lighting are mapped out. MoT testers are told to check noise proofing under the bonnet and exhaust silencers but invited to use their judgement to assess whether the amount of noise generated is “unreasonably above the noise level you’d expect from a similar vehicle with a standard silencer in average condition”. 

If the car is above these levels it should fail the MoT but there is no actual noise test carried out as part of the MoT. It’s a matter of the tester’s opinion. 

Can you report noisy vehicles?

This depends on how frequently and how badly you’re disturbed by a noisy vehicle. If a neighbour has a car that starts up with a roar, the best course of action to start with is to talk to them directly to discuss the issue, as the solution could be as simple as them parking in such a way that their exhaust is pointed away from your house.

If there are local vehicles creating a regular disturbance, however, you may want to record the vehicle type and numberplate and contact your local police force – many will have a dedicated line for disturbances such as this - please remember only to use the Police emergency number for actual emergencies.

If there’s a regular problem in your area resulting from more than just one or two vehicles, it could also be worth speaking to your local council or political representatives and requesting more of a police presence in your area – particularly as loud vehicles often go hand-in-hand with speeding.

Some towns around the country have begun to use ‘noise cameras’, which record the volume of a passing car and take a photo of the registration using automatic number plate recognition or ANPR. If a vehicle is over the noise limit the owner may be sent a fine, much like they would from speeding. These noise cameras are currently undergoing trials – if they prove successful, expect them to become more widespread.

Do you think the regulations for noisy cars should be stricter? Tell us your thoughts in the comments section...