A Guide to UK Car Modification Laws [Infographics]

While there are many ways to upgrade a car’s efficiency and aesthetic appearance, doing some of these modifications on your vehicle could affect its behaviour on the road and also put you on the wrong side of the law.

In the UK, there are various car modification laws in place to ensure upgrades do not cause a public nuisance or put drivers and passengers at risk while travelling on the road.

Here are some of the common car modifications, what effect they have on the vehicle, and how they can be considered legal in England.

Exhaust System

Most drivers modify their exhausts to boost their car’s engine performance. However, others upgrade their vehicle’s exhaust system to amplify the engine’s sound – but this can cause annoyance on public roads.

The vast majority of big-bore and sports exhausts are illegal for use on public roads in the UK due to the excessive noise levels and extra emissions they create.

Under UK laws, the police can take action if your vehicle’s silencer is removed or does not work in the way it was designed, or you are driving in such a way that creates too much noise. If you get caught with an excessively noisy exhaust, you may receive a fine and will be prohibited from driving your car until the offending exhaust is removed.

Number Plates

Personalised number plates are gaining momentum in the UK, but if you are considering changing your current registration, you must ensure that:

  • The front and rear number plates must comply with current legislation regarding size, characters, spacing, font, and format.
  • The number plates must be displayed in a prominent position and should be clear of any obstruction.
  • The number plates’ character configuration is correct and not misleading to other road users.

If your plates do not meet the British Standard for number plates, it could result in the issuance of a fixed penalty notice. Consequently, the Driver and Vehicle Licensing Agency (DVLA) will be notified.

Wheels and Tyres

It is worth noting that changing your wheels and tyres can significantly affect your car’s road-holding, its ability to maintain directional stability over various road surfaces. Therefore, if you consider making modifications to these car components, it is recommended to fit wheels and tyres approved by the vehicle’s manufacturer.

When fitting new tyres, you must ensure adequate clearance between your vehicle’s bodywork and tyre to provide space for suspension movement and prevent the tyres from failing when the steering is turned from lock to lock.


Regarding your car’s lights, it is a legal requirement to have substantially white or yellow lights at the front and a steady red light at the back of the vehicle. Using any other colour of light other than these is not permitted and is considered illegal.

Accordingly, installing red, green, or purple tints on your headlights is not allowed as tinting the car’s lighting system can reduce the efficiency of its reflective material. Using bright neon or flashy lights on your car’s interior or exterior is also not permitted under the law.

Window Tints

Tinting the car’s glass windows is another popular car modification in Britain. But, if you are looking into installing window tint films on your windows, you must meet the legal requirements and ensure that visibility is not obscured.

While there are no restrictions on tinting the back side windows and the rear windscreen, there are limits that must be followed when applying tint to the front side windows and front windscreen. You must install a tint film on the front windshield that lets a minimum of 75% light through. Subsequently, a minimum of 70% VLT is required for tints installed on the front side windows.

If you fail to comply with these criteria, you could be served with a prohibition notice, meaning you will not be able to use your car until the tints are removed. In extreme cases, you can be issued with a penalty notice or even a court summons.

Where can you have window tints installed?

If you are looking for a reputable company that will help you ensure your window tints are within the legal limit stated under UK laws, you could always go to Global Tint.

Global Tint is one of the largest window tinting companies in the United Kingdom that offers window tinting in Nottingham and other UK locations. We also provide our customers with a level of excellence and superior service in caring, maintaining, and installing window tints. If you wish for a free quote today, you may contact us at 0800-158-8005 or visit our website at www.globaltint.co.uk.