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Modified car insurance guide 2024

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From stickers to spoilers, if your car has had any modifications that affect either its performance or its appearance, it’s important you let your insurer know about them. This will ensure that you’ve got the right amount of cover, should you need to make a claim. 

Get the lowdown on how to buy insurance for modified cars, as well as what modifications affect car insurance with our comprehensive guide.

What is modified car insurance?

Modified car insurance is the same as regular car insurance; it just means your insurance provider has taken into account any modifications that have been made to your car.

Insurers will consider any changes that have been made to the look or performance of your car as a modification. This can range from something as simple as fitting parking sensors to more substantial alterations, such as bigger wheels, spoilers, or exhaust upgrades.

If you are in any doubt as to whether something will be considered as a modification, it’s always worth checking with your provider, even if it’s only for something minor like a roof rack.

If your insurer doesn’t know about any modifications to your car, and finds out about them in the event of a claim, your insurance may not be valid and your claim might not be paid.

Most car insurance companies offer insurance for modified cars. However, there are also specialist modified car insurance companies that may suit higher-spec performance cars with more modifications.

Will modifications make my car insurance more expensive?

Modified car insurance go faster stripes
Go-faster stripes look flash but are likely to increase your car insurance (Adobe)

When you tell your insurer about modifications that have been made to your car, they will need to consider whether the changes will affect the risk posed by your car.  

Insurance companies normally assess the risk of a car by checking what insurance group it falls into. Groups are numbered one to 50, with group one being the cheapest to insure and 50 the most expensive. Once a car has been modified – and is therefore no longer a factory model – this rating is invalidated, with insurers arguing they cannot vouch for the quality of the work or know whether it has had a negative impact on the car.

Before they can give you an accurate modified car insurance quote, insurers will need to consider the following:

  • Do the modifications increase the value of your car? This will affect the cost of repairing your car or writing it off after an accident. It will also mean your insurer will need to pay out more money if your car is stolen
  • Will the modifications make it a target for criminals? Some modifications could make your car more attractive to thieves or make it more susceptible to vandalism
  • Could the modifications increase the risk of accidents? If the modifications increase the speed or power of your car, the risk of a collision is likely to be higher. Some modifications might also make your car harder to handle

This means that most modifications will increase the cost of your car insurance. However, there are some that shouldn’t have any impact on cost and a handful that could actually reduce the cost of your insurance.

You might also be asked to supply photos of your car’s modifications.

It’s important to note, however, that exactly how modifications are perceived and the impact they will have on your premiums will vary between different car insurers.

Modifications that can make car insurance more expensive Modifications that can make car insurance cheaper Modifications that shouldn’t affect your car insurance
Custom paintwork or other changes to the car’s exterior – including “go-faster stripes”, decals and sometimes even stickers Engine downsizing Correctly fitted tow bars
Custom LED headlights or under-car neon lights Brake upgrades Correctly fitted roof racks
Short-shift kits Immobilisers Tinted windows, so long as they are legal
Replacement or reupholstered seats Alarms Personalised number plates
Engine upgrades – such as engine control unit remapping or cold air intake Speed limiters Water cooling systems for your brakes
Exhaust upgrades Parking sensors Sounds systems – unless they cost a fortune
Lowered suspension Dash cams Dashboard upgrades
Spoilers and valances Catalytic converter cages Custom or novelty gear knobs
Roll bars Novelty hubcaps
Alloy wheels or bigger wheels
Adding a sunroof
Wheelchair ramps

What is covered under insurance for modified cars?

When you buy comprehensive car insurance for a modified car, you will have the same level of cover as you would when you insure an unchanged car. It just means that the risks posed by the modifications to your car are factored into the price.

Comprehensive car insurance for modified cars will cover:

  • Repairs or replacement costs if your car is damaged in an accident
  • Damage to other cars or property if you were at fault
  • Injury to yourself, passengers and other drivers
  • The theft of your car
  • Fire damage to your car
  • Your personal possessions
  • All of the modifications that have been made to your car, so long as they are legal and have been declared to the insurance company

Some policies may also include additional windscreen cover, breakdown cover, motor legal protection and courtesy cars. However, if they are not included as standard, you can normally pay extra to add them on.

What is not covered by modified car insurance:

Your policy will only cover modifications that are legal. This means you won’t get cover for:

  • Tinted windows that are too dark: Windows must allow at least 70 per cent of light to be legal in the UK, otherwise your visibility could be impaired. The front windscreen must let 75 per cent of light through. This won’t be a problem with factory-fitted tinted windows, but you may encounter problems if you attempt to do it yourself and the tint is too dark. These restrictions don’t apply to the rear windscreen
  • Noisy exhausts: Your upgraded exhaust will be considered illegal if it exceeds 74dB – the noise equivalent of a toilet being flushed. Illegal exhausts are now easier to identify following trials of acoustic cameras
  • Some tinted headlights and tail lights: It’s not illegal to add tints to your car’s lights, but you do need to take care to stay on the right side of the law. Lights cannot be dimmed by more than 50 per cent, and you need to be able to identify the original colour of the light – red in the case of tail lights, and white or yellow for headlights. This is why it makes sense to get this sort of modification carried out by a professional
  • Blue lights: Only emergency vehicles can legally use blue lights – it’s an offence to have any blue lights on your car. This includes under-car lights, as well as lights on your windscreen, washer jets or around your number plate
  • Improperly fitted spoilers: Any spoiler must be securely fitted to your car with no sharp edges exposed. It also must not obstruct your view through the rear windscreen. Police are within their rights to make you remove your spoiler if they consider it to be dangerous

You will also not be covered for modifications that you haven’t declared to your car insurer, whether they are legal or not.

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What is the best insurance for modified cars?

How modifications are treated will vary between insurers, so it’s always important to shop around to get the best modified car insurance.

It’s easy to compare modified car insurance on comparison websites. However, if you’ve got a high-performance car with multiple modifications, it may make sense to get some quotes from specialist insurance companies, too.

Companies that specialise in insurance for modified cars argue they have a better understanding of the needs of ‘modders’ and won’t necessarily regard drivers of modified cars as higher risk. They argue that, in fact, these drivers are passionate about their cars and therefore likely to take better care of them than the average motorist. 

A specialist insurance company might also give you a broader range of insurance options in relation to the payout you get if your car is damaged beyond repair or stolen.

Regular insurance companies will normally only offer you the market value of your car; but you might get a higher payout, or more control over what happens to your car, with an agreed value policy or a policy with a salvage retention clause.

Agreed value policies

This is where you agree a figure with your insurer that it will pay out if your car needs to be written off, or is stolen and not recovered. This means the amount you get back reflects the investment you have made in your car – you don’t just get the market value of your car. As this means the pay out is likely to be higher, agreed value policies are more expensive than regular car insurance. In addition to modified cars, drivers of classic cars, kit cars or converted vans might also choose an agreed value policy.

Salvage retention clauses

If your car cannot be repaired after an accident, or the cost of repairs is unfeasible, your insurer might decide to write off your car. When this happens, your car insurer will keep your car. However, if you can’t face the thought of this happening, your insurer may agree to salvage retention. This allows you to buy the car back and either fix it yourself or reuse some of its parts. However, whether salvage retention is available at the point of claim will depend on the level of damage your car has sustained.



  • Shop around 
  • Keep your mileage down if you can
  • Park your car off-road
  • Add an older or more experienced driver to your policy
  • Consider a black box car insurance policy
  • Agree to a higher voluntary excess (so long as you can still afford to claim)


  • Pay for car insurance monthly – you will pay more for the privilege
  • Auto-renew your policy – shop around for new quotes when your policy is due for renewal 
  • Pay for add-ons you don’t need
  • Add a young or inexperienced driver to your policy
  • Leave it to the last minute – the best quotes are often available a few weeks before you renew

Frequently asked questions about modified car insurance

Yes, but it is essential that you inform your car insurer of any modification straight away, rather than waiting until you renew. You may need to pay more for your insurance, but if you don’t let your insurer know, your policy could be invalidated in the event of a claim. There may also be an admin charge for updating your policy.

To avoid any unpleasant surprises, it’s best to contact your car insurer to find out what impact your desired modification will have on your policy before you go ahead with any work.

If you buy a second-hand car that has already been modified by previous owners, you will still need to tell your insurer, and you may still pay more for your car insurance.

For this reason, it’s vital you check what modifications have been made before buying a second-hand car. Failing to tell your insurer about any modifications – whether you made them or not – could invalidate your policy.

If you buy a new car and select any optional extras, like alloy wheels, they should be fitted in line with the manufacturer’s specifications. This means you shouldn’t pay too much more for your cover, so long as you bought your car from an authorised dealer.

Yes. It’s important that your insurer knows about any modifications to your car, whether it’s a classic or not. If you don’t do this, your car insurance could be invalidated.

Most insurers have now signed up to the Association of British Insurers Winter Tyres Motor Insurance Commitment. This agreement stipulates that policyholders who switch to winter tyres in the colder months do not need to inform their insurer. 

Although changing tyres is, on paper, a modification, insurers are agreed that the added grip winter tyres provide makes them the safest option in ice and snow. 

That said, not all insurance companies have signed up to the commitment, so if you do use winter tyres during the colder months, it’s important to check with your insurer.

This is something of a grey area. Although displaying a sticker on your car seems harmless, your insurance company might argue that if it expresses political opinion, religious belief, or allegiance to a specific sports team, it could make your car a target for vandals. Go-faster stripes, meanwhile, might – rightly or wrongly – suggest you are a higher risk driver.

For this reason, if you want to put any sticker or decal on your car, it makes sense to err on the side of caution and tell your insurer, however excessive it might seem.

If you select an agreed value policy for a modified car, you will need to agree its value with your car insurer. In order to do this, you will need to complete a form from your insurance company, providing information about your car and the modifications that have been carried out. You may also need to supply photos of the inside and outside of the car, as well as of the engine. Receipts and invoices can be used to show how much you have spent modifying your car.

Anything that makes a car more accessible for a disabled driver, such as a wheelchair ramp, altered foot pedals, or steering wheel aids, will count as a modification that needs to be declared to your insurer. Unfortunately, if these modifications increase the value of the car, or the cost of repairing it after an accident, the cost of insuring it is likely to go up.

The main driver’s age is a key factor when calculating car insurance quotes, and young drivers are the most expensive to insure. This is because their inexperience behind the wheel and possible immaturity means they are more likely to be involved in an accident.

As a result, modified car insurance for young drivers could be particularly expensive – especially if the modifications make their car faster, more powerful, or harder to handle.

Many common or basic modifications can be accommodated by mainstream car insurers. However, if you are a real car enthusiast and have made multiple modifications to your car, you may get a better deal and a more understanding approach from a company that specialises in insurance for modified cars.

Molly Dyson


After growing up with a passion for writing, Molly studied journalism and creative writing at university in her home country of the United States.

She has written for a variety of print and online publications, from small town newspapers to international magazines. Most of her 10-year career since relocating to the UK has been spent in business journalism, writing and editing for admin professionals at PA Life magazine and business travel managers at Business Travel News Europe and representing those titles at conferences around the world.

Now an Editor at the Independent Advisor, Molly is an expert in a broad range of consumer topics, that include solar panels and renewables, home improvements and home insurance, and consumer technology such as home security and VPNs.

In her free time, Molly can usually be found exploring the outdoors with her husband and their young son or gardening.