Modified car insurance

Find out how modifications to your car affect your insurance premiums and discover the ways you could save on yours.

Promoted car insurance logo
Get cheap car insurance quotes
Save up to £561 on your car insurance*
Compare over 120 insurance providers
Enjoy rewards
Get a quote

If you’ve changed your car in any way since buying it, it will be classed as a modified car and, depending on the type of modification, your car insurance premiums could go up as a result.

What is a car modification?

Any change made to a car once it leaves the factory floor is considered to be a car modification.

Car modifications are usually made to enhance the speed, performance or look of a car. Some changes might also help drivers or passengers with disabilities gain better access.

What are the different types of car modification?

Car modifications usually fall into two main categories – performance and cosmetic. However, modifications can also include changes that improve the safety and security of your vehicle. Examples of each category can be found in the table below:


  • Upgraded alloy wheels
  • Altered or lowered suspension
  • Turbo or supercharged engine
  • Engine remapping or chipping
  • Fuel upgrades
  • Upgraded exhaust
  • Spoilers


  • Tinted windows
  • Body kit
  • Sunroof
  • Paintwork or body wraps
  • Bonnet bulge

Safety and security

  • Alarms
  • Immobilisers
  • Parking sensors
  • Deeper tread tyres for winter use

Adding a tow bar, roof rack, or wheelchair ramp may also be classed as a modification by your insurer.

Why do modifications affect car insurance?

Insurers work on the assumption that any modification made to the body or mechanics of a car might not be properly guaranteed, which generally results in the risk increasing along with the insurance premiums.

On top of this, if you make cosmetic changes to your car, its value is likely to go up, and the cost of repairs and spare parts may become more expensive. This means your car insurance premiums will rise as a result. Cosmetic changes could also make your car more attractive to thieves, as could installing expensive tech, which will again push up your premiums.

Similarly, if you improve your car’s performance so it can now go at faster speeds, there’s a greater risk of you being involved in an accident and making a claim, so your premiums will be higher.

What does modified car insurance cover?

Modified car insurance covers you against the same risks that standard car insurance will cover you for, but it will also cover the additional parts you’ve modified your car with.

You’ll also be able to bolt on the usual optional extras such as:

  • Breakdown cover
  • Windscreen repair cover
  • Lost key cover
  • Courtesy car cover

What is the real value of a modified car?

Car modifications often result in the value of your car increasing significantly, and this can make your insurance costs more expensive. However, it’s not always easy to calculate the value of a modified car which is why your insurer may offer “agreed value cover” or “salvage retention”.

With agreed value cover, you agree a set value with your insurer. Your insurer will then pay out this amount if your modified car is stolen or written off, regardless of its original market value.

With salvage retention, you can choose to buy back your car from your insurer if it’s written off. Cars are written off when the repair costs are greater than the cost of replacing the car.
The most expensive car modifications to insure

Some modifications are riskier than others which means they are more likely to increase your car insurance premium.

To give you an idea of the most expensive modifications to insure, we’ve compared the cost of a car insurance policy without modifications against the cost of the same policy once certain modifications have been added.

The quote without modifications came to £280.50 per year, and the table below shows the five most expensive modifications that we looked at:

ModificationPricePercentage increase (from original quote)
Chipped engine system£430.7053.5%
Non-standard paintwork£419.8049.7%
Rear spoiler£385.9037.6%
Wider wheels£370.9032.2%
Bonnet bulge£351.8025.4%

Are there any modifications that can get me a discount on my car insurance?

Yes, if the modifications you’re making improve your vehicle’s security and/or safety and could reduce the risk of an accident, your insurance premiums may be reduced.

Modifications that could affect your insurance in a positive way include:

  • Parking sensors – can help to reduce the risk of minor collisions.
  • Installing an alarm or immobiliser – can help to reduce the risk of theft.
  • Deeper tread tyres – can help you to drive more safely in wintry conditions.

How to cut the cost of modified car insurance

There are a number of steps you can take to reduce the cost of modified car insurance:

  • Increase security. If your car isn’t currently fitted with an alarm, think about adding one to reduce your premium.
  • Park your car in a secure location. Cars kept in a locked garage or on a secure driveway are usually cheaper to insure.
  • Limit your mileage. Letting your insurer know about a reduction in your mileage could result in cheaper insurance.
  • Increase the excess. Agreeing to pay a bigger voluntary excess could make your overall premium cheaper, but remember your insurer won’t pay out for a claim that costs less than your excess. Be careful about making it too high as it could leave you out of pocket if damage occurs.
  • Add experienced drivers. Adding an older and more experienced driver to your policy could help to lower the premium.
  • Limit optional extras if you don’t need them. Think carefully about which optional extras you really want as adding extra protection to your policy will generally push the price up too.
  • Avoid paying monthly. If you can, try to pay for your premium in one go as you’ll pay interest if the premium is spread out over the year.
  • Take an advanced driving course. Completing an advanced driving course, such as the Pass Plus scheme, could result in your insurer adding a discount to your premium.
  • Shop around. Don’t simply choose to renew your car insurance when it’s up for renewal as you could end up paying more than you need. Shop around and compare your options to find the best deal.

What if my car already had modifications when I bought it?

If you’re buying a brand new car from a dealership and have paid extra for certain modifications, it’s unlikely your car insurance premium will be significantly affected. This is simply because the modifications were fitted by the manufacturer itself.

However, if you’re buying a used car that has been modified by someone else, it’s important to find out exactly what modifications have been made so you can pass this information onto the insurance provider. The insurer will want to know about every modification made to the car in order to properly assess its risk and calculate the insurance premiums.

You’ll need to check if your insurer will cover the modifications that have been made and be prepared for your premiums to increase if they relate to the look or performance of the car. If, on the other hand, the modifications enhance the security of your car, you may see your premium drop.

Do I have to tell my insurer if my car has a modification?

Yes, it’s important that you tell your insurer as soon as possible if you are planning any modifications to your car. That way you can check whether your insurer is still willing to offer you protection or whether you will need to find specialist car cover from elsewhere.

As each insurance provider will have its own guidelines around modifications, contacting your own insurance provider is the only real way of ensuring your protection remains in place at all times. If you don’t tell your insurer about any modifications, you risk invalidating your cover.

Do I have to go through a specialist provider if I have car modifications?

You don’t have to, particularly if you’re only making small modifications such as upgraded alloy wheels. However, if your modifications are more substantial, seeking out a specialist insurer can be beneficial as it may have more knowledge about the modifications made to your car or the modifications you plan to make. Specialist providers can also offer important cover benefits as standard that other providers only offer as optional extras.

Some specialist insurers of modified cars will look at the value, power and driver’s experience when calculating the insurance premium rather than the cosmetic or mechanical changes. Do some research to see which insurer can offer you the best cover.

Can I make a modification to my car mid-policy?

You can, but you must inform your insurer about the modification as soon as possible – don’t wait until it’s time to renew. You may have to pay extra for your premiums as a result of the modification so it’s worth considering this carefully before going ahead with any changes. You may also have to pay an admin fee.

Is modified car insurance cheaper?

In most cases, modifications are likely to increase your insurance premiums, not lower them. However, if the modifications to your car increase its security or help you to drive more safely, you may see a reduction in the amount you pay for car insurance.

What happens if you don’t declare car modifications?

If you don’t declare car modifications to your insurer, you could invalidate your cover and your insurer may refuse to pay out if you later make a claim.

Which cars are most frequently modified?

Classic cars are often modified by their owners, but other popular cars to modify include the VW Beetle and the Mini, the Ford Fiesta and the Mazda MX-5.

Bottom line

Car modifications should always be considered carefully. If you’re planning to make any changes to your car, no matter how small, it’s always worth talking to your insurer first to see how it could impact your insurance costs. Smaller, more popular modifications are more likely to be covered by standard car insurance. However, if you plan to make more substantial changes, such as installing a turbo engine, you may need to approach a specialist insurance provider.

Finder survey: What proportion of Brits would consider upgrading their car to have tinted windows?

Tinted windows5.26%12.87%17.37%26.09%30.1%
Source: Finder survey by Censuswide of 1032 Brits, December 2023

Frequently asked questions

The offers compared on this page are chosen from a range of products we can track; we don't cover every product on the market...yet. Unless we've indicated otherwise, products are shown in no particular order or ranking. The terms "best", "top", "cheap" (and variations), aren't product ratings, although we always explain what's great about a product when we highlight it; this is subject to our terms of use. When making a big financial decision, it's wise to consider getting independent financial advice, and always consider your own financial circumstances when comparing products so you get what's right for you. Most of the data in Finder's comparison tables has the source: Moneyfacts Group PLC. In other cases, Finder has sourced data directly from providers.
*Based on data provided by Consumer Intelligence Ltd, (Mar ’24). 51% of car insurance customers could save £539.54

Written by

Rachel Wait

Rachel Wait is a freelance journalist and has been writing about personal finance for more than a decade, covering everything from insurance to mortgages. She has written for a range of personal finance websites and national newspapers, including The Observer, The Mail on Sunday, The Sun and the Evening Standard. Rachel is a keen baker in her spare time. See full profile

More guides on Finder

  • Dude, when’s my car insurance?

    We explain how to find out when your car insurance is up for renewal and how to avoid the hefty fines for missing it.

  • Cat S insurance

    Learn how to find insurance for your Cat S write-off, average cost and whether you can keep your category S car.

  • Admiral car insurance review

    Compare and review all the policies on offer from Admiral car insurance and see if it provides cover that suits you.

  • Fiat 500 Insurance Group

    Find out which insurance group your Fiat 500 belongs in, how much it should cost to insure and how you can save on your premiums.

  • Cheapest car insurance in the UK

    Good car insurance doesn’t have to be expensive. Compare cheap car insurance quotes to start saving today.

  • Direct Line car insurance review

    Compare Direct Line’s car insurance options with our analysis and review. Find out what’s covered and how to make a claim.

  • RAC car insurance review

    Compare and review RAC car insurance and find out if it’s the right cover for you. Discover policies and how to save on your premiums.

  • Tesco Bank car insurance review

    Compare and review Tesco Bank car insurance and see if it has the right policy to protect you behind the wheel.

  • Car insurance exclusions

    Find out what car insurance won’t cover so you can avoid any nasty surprises at claim time.

  • Get agreed value car insurance quotes online

    Find out how agreed value car insurance works and if it’s the right option for you.

Go to site