Car Modifications & How They Affect Your Insurance
What impact do car modifications have on insurance in the UK? Car modifications can lead to increased insurance premiums in the UK. This is due to a combination of increased risk and the higher repair and replacement costs associated with modified cars.  You must disclose all car modifications to an insurance provider when purchasing car insurance. Failing to do so could void your insurance policy if you are driving a modified or customised vehicle.

sports car

Car Modifications & Insurance Premiums

Car modifications tend to drive up the cost of an insurance premium. If you want to customize or upgrade your car in any way, bear in mind you most likely will have to fork out some extra cash to get the car insured. Let's take a look at how car modifications affect car insurance in the UK.

Increased Premiums

In most cases, car modifications are result in higher insurance premiums. There's no getting away from this. Modifications tend to increase the risk associated with the vehicle. And, this is bad news when it comes to premiums. Higher risk equals higher cost for the insurer provider. Modifications are often associated with aggressive driving, speeding, and alterations that lead to higher repair costs in the event of an accident.

Altered Vehicle Value

Many modifications, such as engine upgrades and custom paintwork increase the value of the car. This means that in the event of an accident and damage to the car, the insurance company would have to pay out a higher value to replace or repair the vehicle. This means premiums are higher to reflect the increased value.

Risk Assessment

Insurance companies assess the level of risk associated with every car, And, modifications have an impact on the risk assessment process. For example, performance enhancements like turbocharging or supercharging increase the likelihood of accidents due to higher speeds. And, visual modifications often attract more attention and lead to an increased risk of theft or vandalism.

mechanic modifying a car engine

Specialised Parts

Modified cars used specialised parts. And, finding replacement parts for modified vehicles is more expensive and time-consuming compared to regular cars. Insurance companies take this into account when setting premiums and this drives prices upwards. More time and more money means more expensive premiums.

List of Car Modifications

What are the most common modifications people make to their cars in the UK? And, what modifications can have an impact on your car insurance policy? Here's a comprehensive list of the most common car modifications in the UK – and how they work. If you're planning on customising your vehicle, here's what you need to know.

Turbo & Supercharging

Turbocharging and supercharging involve forcing compressing air into the engine. This significantly increases power output and torque. These modifications boost acceleration, overall engine performance, and the driving experience. In effect, they make the car more powerful

Transmission & Gear Changes

Modifying the car's transmission or gear ratios allows you to tailor the performance of the car. These changes are made to optimize acceleration and top speed. These changes are popular for enhancing the overall driving experience and matching the car's capabilities with a driver's preferences.

Exhaust Changes

This is another very popular car modification. Especially amongst boy racers. Upgrading the exhaust system involves replacing original factory components with high-performance alternatives. These boost engine performance and create a distinctive, and often more aggressive exhaust noise.

Air Filter

This is a relatively straightforward and cost-effective modification. Engine airflow can be improved by installing a high-flow air filter. This results in enhanced fuel efficiency and improved power output. It not only boosts performance but helps long-term engine health by keeping harmful particles out of the intake.

flashy looking modified car

Body Kit

Body kits are used to transform the aesthetics of a car. They add side skirts, custom-designed bumpers, and other fancy components. Body kits are all about looks and are favoured by car enthusiasts who want a unique and distinctive style.


Suspension modifications can enhance various aspects of a car's performance, including handling, ride comfort, and off-road capabilities. Selecting the right suspension components aligns your car with your driving needs and preferences.

Seat Replacement

This involves swapping out original stock seats with aftermarket seat options. This car modification can improve comfort, style, and feel. Especially during extended drives and is a popular choice for those who spend extended hours on the road. Custom seats are available in a variety of materials and designs. For more, check out Car Seats – Leather vs Cloth.

Roll Bars & Roll Cages

Roll bars and cages are safety features that provide crucial protection in the event of a rollover. They significantly enhance driver and passenger safety when driving – especially during extreme driving scenarios where excess speed is involved. They boost a car's structural rigidity, and integrity during aggressive driving maneuvers.

Dashboard Changes

Customizing your dashboard with new gauges, screens, or control systems is a popular car modification among enthusiasts. It's a cost-effective way of personalising appearance and adding functionality. It allows car owners a simple method of personalizing their car's interior. The most common dashboard modifications are advanced infotainment systems and connectivity accessories.

Upgraded Braking Systems

Upgraded car brakes are another popular option. Upgrading the braking system with larger or high-performance components results in shorter stopping distances, improved overall braking performance, and better safety. These modifications often involve new and improved brake pads and rotors. They're often a necessary upgrade in high-performance cars.

Alloy Wheels

Alloy wheels are a very popular car modification. They not only enhance the aesthetics of the vehicle but can also improve handling, fuel efficiency, and the overall driving experience. Alloy wheels are often preferred for their lower weight. This reduces rolling resistance, improves suspension, and leads to a smoother and more efficient ride. And, who doesn't want fuel efficiency in this day and age?

car with alloy wheels

 Spoilers & Skirts

What about car spoilers and skirts? These aerodynamic components add downforce, enhance stability, cornering, and of course - visual appeal. Especially in performance 'muscle' vehicles. Spoilers can be tailored to a car's specific design, enhance the overall look of the car, and create a more balanced and controlled driving experience.

Vehicle Lights

Upgrading headlights, rear lights, or interior lighting is another highly popular car modification. Light upgrades can improve visibility, road safety, and the overall appearance of your car. Advanced lighting technologies, such as LED or HID, not only increase visibility but also reduce energy consumption and ensure a longer-lasting and more efficient lighting system.

Tinted Windows

Window tinting provides privacy, reduces glare, and offers protection against harmful UV rays. They have a practical and stylish appeal. Tinting can also help maintain a cooler interior temperature, reducing the load on your air conditioning system and improving fuel efficiency. In the UK there are restrictions on the amount of tinting you can have on your front windshield and front side windows.

LPG Conversion

Converting to Liquefied Petroleum Gas (LPG) offers cost savings and reduced emissions. It can be more environmentally friendly compared to other fuel options. LPG conversions typically involve installing a secondary fuel system, allowing you to switch between petrol/diesel and LPG. This provides flexibility and potential long-term savings.

Bonnet Vents

Bonnet vents boost engine cooling, especially in high-performance and turbocharged vehicles. They help prevent overheating and ensure optimal engine performance and cooling. Bonnet vents not only enhance cooling but can also reduce air turbulence, contributing to better aerodynamics and stability.

Air Conditioning

AC modifications can deliver a more comfortable and efficient cooling system. They are used to enhance overall driving comfort - especially in hot summer conditions. An upgraded air conditioning system not only cools the car cabin quickly but can also filter the air more efficiently, removing allergens and pollutants for a healthier and more enjoyable driving experience. Happy days.

Rear Diffusers & Front Splitters

Diffusers and splitters are aerodynamic additions that are used to optimize stability, reduce drag, and enhance the car's handling. Especially, for high-speed and high-performance cars. They are often seen in racing cars. They redirect airflow around the car and create better downforce This can improve grip and cornering performance for a safer and more exciting driving experience.

Intercooler Upgrades

These modifications are used to enhance the intercooler's efficiency. They are crucial for turbocharged engines, as they ensure the engine receives the cooler denser air it needs to perform. Intercooler upgrades typically involve increasing its size, improving airflow, and sometimes relocating it to a more efficient position.

car driving on open road

 Fuel System Changes

Another popular car modification involves making changes to the fuel system to improve fuel efficiency, horsepower, and torque. These changes deliver more responsive and efficient engine performance. Again, this modification is more applicable to high-performance vehicles. Examples include upgrading the fuel injectors, fuel pumps, and fuel lines.

Specialised Paintwork

Custom car paint jobs provide a unique, personalized look They allow car owners to express their individuality and apply a unique color and style to their car. And, yes, this is classed as a car modification by insurance companies. Whether it's a dazzling metallic finish, go faster stripes, or eye-catching colour schemes - specialised paintwork can turn a mundane-looking car into something straight out of the 'Fast & Furious' film series.

Wheel Arches

Wheel arches can be widened to accommodate larger tyres. This car modification is made to potentially improve traction, and off-road capability, and to elevate the car's stance. Some car owners feel it gives the car a more aggressive appearance. This modification often involves having to reinforce the arches if the vehicle is to be used for off-road driving.

Stripes & Badges

Decorative stripes and badges are a popular choice among car enthusiasts. They are added to personalize a vehicle's aesthetics and to show off the owner's style and motorsport interests. They are used to add individuality and to personalize a car. Popular additions include classic racing stripes and manufacturer badges. They can add character and identity to a vehicle.

How Do Car Insurance Companies View Modifications?

What is the perspective of car insurance companies? How do they view modifications? And, how do these car modifications impact insurance policies? Any modification that affects the performance or look of a vehicle has an impact on your insurance policy. And, all these changes will be considered and assessed by an insurance provider.

woman driving a car

Whenever you apply for a new car insurance policy, one of the first questions you will be asked is – has the car been modified in any way? This is because when an insurer sets the price for a car insurance policy they have to consider all factors that influence the likelihood of the car being involved in an accident or being stolen. And, car modifications play a key role in these considerations.
Car insurance providers will review any modifications made to ensure the policy provided and the price quoted are suitable to cover the level of risk for that specific car. Insurers understand that modifications can enhance a vehicle's performance and aesthetics, but they also recognise how they can increase the risk associated with the vehicle. And, more often than not, car modifications will increase the cost of a car insurance policy.
That is why you must balance the desire to make changes to your car against the potential impact and cost of insuring the vehicle. And, most importantly transparency is key. You must be completely open and honest when discussing car modifications with a car insurer to ensure your policy provides the right level of protection for your unique vehicle.
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