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What Car Modifications Affect Insurance?

Written by, Marija Petkova

Updated August, 3, 2022

What car modifications affect insurance?

Any non-standard car modifications, like changes to the brakes and suspension, wheels, engine, and even car interior can increase the cost of your vehicle insurance.

To get a better understanding of how each modification can affect your insurance and in what way, read on. 

What Is Classed as a Modification on a Car?  

A car modification is any change made to a vehicle that enhances its performance and/or improves its aesthetics and isn’t part of the original factory specifications. 

It can be anything from paintwork to something that entirely changes the mechanics of the vehicle, like an engine swap. That said, not all modifications will affect the cost of your insurance, but most will, regardless of how big or small the change is.

Performance modifications

Performance modifications are changes made to a vehicle that boost its power, improve its handling, and/or ensure better fuel efficiency. Some of the most popular performance modifications include:

  • ECU remapping
  • Installing performance tyre
  • Upgrading the braking system
  • Improving air intake
  • Updating the exhaust
  • Wheel alignment

Worth noting: Certain car modifications can not only result in higher insurance premiums but might also increase your vehicle-related expenses. For example, adding a turbocharger may improve performance but it will also cause your engine to burn more fuel. 

Cosmetic modifications

Cosmetic modifications are changes made to the car’s appearance, purely for looks, such as:

  • Fitting sport seats
  • Upholstery on dashboard
  • Stripes, badges, decals
  • Paintwork
  • Windows tint
  • Underbody neon lights

What Car Modifications Affect Insurance?

Here’s a car insurance modifications list of changes that can affect your insurance (based on a MoneySupermarket survey conducted between May 2021 and April 2022).


Small bodywork modifications may raise your premium by 10-15%, but if you want complete body kit modification, it can increase your premium by 57% because it can significantly increase the value of the vehicle. 

Another reason why bodywork modifications lead to higher insurance costs is that they can affect the car’s aerodynamics and its safety in case of an accident. 

Modified car lights  

Under-car neon lights are popular among car enthusiasts and can increase your premium by 12%. Keep in mind that flashing under-car lights are not allowed in the UK. 

Lowered car suspension

Shaving a few inches off the height of your automobile can result in faster accelerations and quicker stops. However, these changes will cost you an extra 25% on your insurance. 

Engine remapping

Engine remapping can increase power and torque, improve fuel efficiency, and increase your insurance by 20%.

Enhanced car sound systems

Modifications to a vehicle’s sound system will drastically improve audio quality but make the car more appealing to thieves. Because of that, your insurer can up your premiums by 10-15%.

Does painting your car affect insurance?

Most insurers class changing the colour of your car as a modification. Paintwork can increase your insurance by 15%-36%.

Are stickers classed as a modification?

Stickers are sometimes considered modifications and can increase your insurance premium by 9%

Does changing wheels affect insurance?

Standard alloy wheels will not affect your vehicle insurance, but if you change their colour or upgrade them, your premiums will likely rise because these changes can increase the likelihood of the wheel being stolen. On average, your rates would go up by 8%.

How much does a spoiler add to insurance?

Spoilers can increase the cost of your insurance by around 23% because they allow vehicles to go faster and increase the likelihood of an accident.

Does having a subwoofer increase car insurance?

A subwoofer can increase your insurance premium by 10%-15%

What Happens If You Don’t Declare Car Modifications?

Not declaring modifications on car insurance will almost certainly invalidate your policy, regardless of whether the omission was intentional or not.

Policyholders are required to disclose all modifications when taking out a policy and inform their insurer as soon as possible when they make changes to their vehicle that might affect their insurance. 

In some cases, you might need to contact your insurer before making changes to your vehicle because some insurers refuse to cover certain modifications.

How Can I Get Cheap Modified Car Insurance?

There are a few ways to lower your premiums with a modified car, including: 

  • Safe storage 

Parking your car in a garage or a place where there’s less of a risk that it will be stolen or damaged can lower your premiums.

  • Pay annually

It’s cheaper to pay for insurance annually because insurers charge interest when policyholders pay monthly.

  • Add a second driver 

Adding a second driver means you’ll spend less time on the road, which reduces the probability of having an accident and making a claim. 

  • Lower your mileage 

The more miles you travel, the greater the chance of an accident, which means higher insurance premiums.

  • Black box technology 

Fitting a black box device that lets your insurer monitor your driving behaviour can reduce the cost of your insurance, but only if you’re a safe driver.

  • Modifications that improve safety

Modifications like anti-roll bars, downsizing the engine to improve car efficiency, better braking system, and suspension upgrades to improve handling can decrease the cost of your insurance because it improves the overall safety of the vehicle.

If you want to learn more about black box insurance and find out if it’s a good fit for you, check out this comprehensive article.

Car Modifications That Don’t Affect Insurance

Certain car mods don’t affect insurance in the UK. These modifications don’t affect the performance of the vehicle or its value.

For example, drivers need to change their wheels in the winter and summer for better grip. This won’t increase the cost of the insurance as long as the new wheels are the same size or smaller than the original wheels.

Drivers can also make cosmetic changes to their car, such as adding a decal or paint jobs, as long as these changes do not affect the car’s performance or significantly increase its value. 

Aftermarket accessories, such as a GPS or a new stereo, won’t affect the cost of the insurance as well. 

Other car mods that don’t affect insurance are:

  • Dash cams
  • Steering wheel locks
  • Catalytic converter cages
  • Alarms and immobilisers
  • Tracking devices
  • Parking sensors

Bottom Line 

Most car modifications will certainly affect your insurance. Enhancing performance and any cosmetic changes that may increase the value of your car will, in turn, increase the cost of your premiums. There are some modifications, like parking sensors, that can lower your premiums because they improve vehicle safety.

Frequently Asked Questions And Their Answers

What car modifications are legal in the UK?

In the UK, drivers can lower the suspension of the car, add neon lights, install spoilers, and tint their windows (but only to a certain degree), among other things.

Do you have to declare modifications on car insurance?

Insurers require policyholders to declare all modifications made to the car when taking out a policy. You’ll have to inform your insurer if you make any changes to your car that improve performance or increase its value.  

Do modifications void insurance?

In general, any changes you make that break the law might void your insurance.

How modifications may affect insurance?

Modifications can either increase or lower your premiums, depending on whether they improve performance, increase the car’s value, or improve safety. 

Do window tints affect insurance?

Generally, tinted windows won’t raise your insurance premiums. However, different insurers have different rules and you will need to inform your provider in case it requires a policy change.

What car modifications affect insurance?

Common modifications that may have an impact on your insurance include changing the type and size of the engine, modifying the suspension or wheels, paintwork, bodywork, and engine remapping among other things.

My name is Marija, and I'm a financial writer at DontDisappointMe. Although finance might not be everyone's cup of tea, my 10+ years of working in one of the biggest banks in my country, and my interest in extensive research on everything finance/investment-related, have made me somewhat of an expert in the field (if I do say so myself). No longer having the passion to work in a corporate setting, I decided that I couldn't let all of this knowledge go to waste so I started writing. And, here I am! Today I try to share my knowledge with my audience in the hopes of making this topic as simple and interesting as possible. In my leisure time, I like spending time with my family and travelling to new locations.