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Modified car insurance covers your car if you’ve had it altered in any way from its original manufacturer specification.
It’s a standard car insurance policy but the premium factors in any changes that have been made to the vehicle, such as fitting alloy wheels.
When you get a quote through MoneySupermarket we’ll ask you whether your car has any modifications after you’ve confirmed your car registration, name and address.
Always consult your insurance company before you make any modifications. They can tell you what impact, if any, the changes will make to your policy and premiums
Insurers believe that modifications done outside the factory cannot be guaranteed and may compromise the integrity of the vehicle which can increase your premiums
Insurers use car insurance groups to set premiums and modifications can potentially void your rating or push your car into a higher group, which will increase your premium
When evaluating different types of modifications, insurers will assess whether the modifications increase the risk of theft, accidents, and/ or repair costs
There are several types of car modifications, which can affect your premium differently:
Changes that increase your car’s power will usually result in higher premiums as insurers perceive that there is a greater risk of an accident.
Performance modifications include:
Engine remapping or retuning
Adding turbochargers
Exhaust system changes
High-performance air intakes
Changes to your car’s appearance, even minor ones such as fitting alloy wheels, could have an impact if they increase the likelihood of your car being stolen, cost more to repair or push up your car’s value.
Cosmetic modifications include:
Alloy wheels
Tinted windows
Resprays
Vinyl wraps
Spoilers
Sports seats
Practical changes may not increase your insurance premium unless they are significant alterations or increase your car’s value. In some cases, practical alterations, such as fitting parking sensors, may reduce your car insurance.
Practical modifications include:
Tow bars
Roof racks
New or upgraded sound and infotainment systems
Parking sensors
Reversing cameras
Trackers
Winter or all-season tyres
Wheelchair adaptions
Some modifications can result in lower premiums if they reduce risk while others can raise premiums due to:
Increased repair costs
Performance risks
Attractiveness to thieves
The insurance group rating
This is why if you do make any custom changes – or you purchase a vehicle that has been customised from the factory model – you should let your insurance provider know.
Failure to do so could result in your policy being invalid when you come to make a claim.
The level of cover you take out (third-party, third-party fire and theft or comprehensive) will affect what is included for modified vehicles. Generally, you should be able to get cover for:
A fully comprehensive car insurance policy should provide cover for you and your vehicle against a range of insured events, including fire, theft, and more
This cover will also extend to any modifications you’ve had made or installed – so long as you’ve declared them to the insurer
You’ll also be covered for any damage you do to a third party, their vehicle, or their property
Car insurance policies also offer a range of extra features like car key cover, windscreen cover, and breakdown cover – some are included as standard, while others are usually available at an extra cost
The way modifications can affect your car insurance price depends on a number of factors. Typically, however, modifying your car will increase the cost of your car insurance.
Reasons for increased price:
Increased risk of accidents or theft
Increased value of the car
Insurers can't guarantee the quality of any modifications
Increased repair costs
Exceptions:
Modifications that make your car safer or improve security may reduce your premiums
Bear in mind that not all insurers treat modifications the same way so it’s worth shopping around or using a specialist provider.
If you’ve had your car modified, you might want to consider the following to help balance the higher insurance costs:
Paying your car insurance premiums annually usually works out cheaper than spreading the cost over 12 months
Paying a higher voluntary excess tells insurers you’re unlikely to bother with small claims that wouldn’t be worth the cost
If you can go for over a year without claiming you’ll start to accumulate a no-claims discount on future premiums
The less time you spend on the road the lower your chances of being involved in an accident, so giving a lower estimated mileage can cut your premiums
Pay-as-you-go car insurance lets you pay for cover either by-the-mile, by-the-hour or based on your driving, and can be a cheaper alternative for some drivers
You might be able to find a cheaper deal on your car insurance if you compare quotes rather than auto renewing your policy
If you’ve made some modifications that significantly alter your car’s performance or value you might need to consider an insurance provider that specialises in modified cars rather than a standard insurer.
Not all modifications result in higher premiums. If you make upgrades, such as fitting a reversing camera or a Thatcham-approved alarm, you potentially reduce your level of risk which should reduce premiums.
Before making any modifications to your car, check whether they are legal. There are rules about tinted windows and noise restrictions for exhausts, for instance. If you decide to have your engine remapped you need to ensure it doesn’t make your car’s emissions non-compliant. Even something as simple as upgrading your wheels counts as a car modification, and if they’re more expensive they’ll cost the insurer more to replace and might be attractive to thieves.
Sarah Tooze Car & Van Insurance Expert
MoneySuperMarket has won the Feefo Platinum Trusted Service Award, an independent seal of excellence, which recognises businesses that consistently deliver a world-class customer experience.
Car insurance is almost always more expensive for younger drivers, and this is true for modified cars too. Unfortunately for young drivers, they are associated with a higher claim risk due to their inexperience on the road – as a result, insurers charge higher premiums.
If you’ve modified a car after purchasing it, you just need to inform your insurer of all the work that has been done to the car so they can factor it in when deciding your premiums.
Car safety and security measures are modifications which may lower the cost of insurance as they reduce risk for the insurer. For example:
A car alarm or an immobiliser: Could help prevent your car from being stolen
A vehicle tracking device: Could help the police to recover your car if it’s stolen
Parking sensors or a reversing camera: Could reduce the risk of a low speed manoeuvring accident
Before fitting any of this technology though it’s a good idea to speak to your insurer to check whether a reduction will be made and how much it will be.
Yes, you can customise your vehicle whenever you choose, but you must notify your insurance company.
That’s because the existing insurance policy covers your car for its original condition. Once that is changed, the policy needs to be adjusted to suit or you risk invalidating the insurance.
Your insurer will decide how the modifications affect your premium.
There are some cases where you may need a specialist modified car insurance policy.
Most minor, legal modifications can be covered by standard car insurance. However, some modifications can affect which insurance rating group your car fits into. This means that your cover may be more expensive or, in some cases, a modification could void your cover, especially if you fail to tell your provider about it.
If you have plans to make modifications to your car there are specialist policies available that will cover both big and small modifications with no hassle. These special policies are priced differently to standard car insurance and may have different terms so it's up to you to decide whether the cover is worth the cost.
At MoneySuperMarket, we do not offer quotes for specialist policies. However, we can find you quotes for car insurance providers that will cover existing modifications made to your car.
Yes, you must inform your insurer if you fit a tow bar, even if it’s a removable one. If you don’t then you risk your insurer not paying out if you need to make a claim or your insurance being voided.
If you don’t tell your insurer about car modifications then you risk:
Invalidating your policy: Your insurer has based your premium on the car in its original, unmodified condition
Rejected claims: Your insurer may refuse to pay out if you have an incident and they discover you had not informed them about a modification
Higher premiums: If your policy is cancelled you’re likely to face higher premiums when you next take out car insurance
No, insurers don’t consider a personalised number plate a modification but you will still need to notify your insurer, and an admin fee may be charged to update your records.
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Yes, you can earn SuperSaveClub rewards when you buy car insurance through MoneySuperMarket.
This includes:
Up to £15, which you can withdraw as a pre-paid Mastercard or a gift card for brands like Sainsbury's and Amazon.co.uk
Free Days Out pass (worth £180), which gives free entry to a range of UK attractions
Cashback of up to 10% when you spend at brands including eBay, Just Eat and Argos
To earn SuperSaveClub rewards on purchases you must:
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Be signed in to your account when you make the purchase
More information can be found on our SuperSaveClub homepage.
Yes, car insurance is included in our Super Save Price Promise.
If you buy through us then find the same deal for less we will:
refund the difference
give you a gift card worth up to £20
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Reviewed on 11 Dec 2025 by
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Accurate as of 10 December 2025.
