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Modified car insurance

Is your car modified? Compare car insurance quotes and get the right cover for your upgrades and enhancements

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Modified car insurance

What is modified car insurance?

If your car’s been altered to look, feel, or drive differently from its original factory and manufacturer’s specification, then it’s classed as ‘modified’.

When you're buying car insurance, your insurer will need to know about any modifications that’ve been made to your car in order to insure it correctly.

If you don’t tell your insurer about the modifications, you run the risk of not being properly insured and your provider could refuse to pay out in the event of a claim.

Popular car modifications include alloy wheels, tinted windows, suspension and engine changes, roll bars, spoilers and extra or adaptive headlights.

What does modified car insurance cover?

Modified car insurance works in exactly the same way as a standard car insurance policy. It simply also factors in the extra parts you’ve added or changes you’ve made to your car.

So, just like standard motor insurance, modified car cover insures against events like accidental damage, fire and theft.  And you’ll be able to choose from extras like breakdown cover, courtesy car and windscreen cover.

There are some modifications which are illegal and won’t be covered under your car insurance, though. For example, if you’re thinking about getting tinted windows installed, then to stay on the right side of the law, (and for safety reasons), the front windscreen must let in at least 75% of light. Other modifications like altered exhausts that exceed a noise limit of 74 decibels, coloured tints on headlights and improperly fitted spoilers are also illegal.

Before making any changes to your car, you should of course check that the modification is legal, but you may also want to contact your insurance provider to see if they’ll cover the modification and find out how it’ll impact your premium.

What modifications can affect car insurance?

The majority of modifications will have an effect on your premium.

That’s because when an insurer sets a price for a policy, they take into account:

Anything that affects the car’s value

Some modifications - like wheel upgrades - add value to your vehicle, which means that repairs and replacements are going to cost your insurer more in the event of a claim.

Factors that might increase its chances of being involved in an accident or stolen

Insurers consider that some modifications put your vehicle at increased risk of accident, theft or even vandalism.

Modifications that can increase your premium include things like:

  • A re-engineered engine for fast and powerful performance. It could put you more at risk of being involved in a high-speed incident
  • Lowering the suspension - though it can make a car handle and corner better, it could get in the way of important car safety systems, such as anti-lock brakes. If suspension is too low, it can adversely affect steering too
  • Body kits and spoilers could compromise vehicle safety as they can break and shatter easily in accidents
  • Expensive wheel alloys - if they get damaged, they’re usually more costly to replace than the factory standard. Enhancements like this can also make your car more of a target for thieves
  • Remarkably, even a sticker on your window that shows a political or fan allegiance (for example a football club you follow) could be classed as a modification by some insurers. It could make your car a target for vandals who have opposing views to you. Plus, sporting something like racing stripes on your car’s bodywork could make your insurer see you as a riskier driver

On the other hand, some modifications can actually reduce your premiums because they improve safety. Things like:

  • Parking sensors
  • An immobiliser, tracker and dash cam

How to get the right insurance coverage for a modified car

It’s always a good idea to compare a range of insurers because they’ll all have different rules and criteria as to how they treat modifications.

In cases where you’ve made a lot of changes to your car, a specialist insurer, used to dealing with modified cars, could offer you a good deal. Insurers like this often recognise that owners and enthusiasts who’ve spent a lot of time and money modifying their car may be more likely to look after it.

The changes you make to your car could increase its value beyond what you paid for it, or its market value. In such cases, you can talk to the insurer about an agreed value policy and salvage retention. These are types of insurance that help to protect your investment should your vehicle be written off.

Agreed-value policies

An agreed value policy recognises the time and money spent on a modified vehicle. You set the value of your car with the insurer and they’ll pay out that amount if your car’s a total loss, regardless of its market value. Agreed value policies tend to be more expensive than standard car insurance policies.

Salvage retention

If repairing your vehicle would cost more than replacing it, your insurer will write it off. Some insurers will offer salvage retention, which lets you buy it back to save it from being scrapped. That way, you may be able to re-use some of the parts or even repair the damage to your car yourself.

How to determine the value of a modified car for insurance purposes

When you take out an agreed value policy with your insurer, you’ll come to an agreement with your insurer as to its value.

To agree the value with you, the insurer will want details of your vehicle. You’ll need to fill out a form letting the insurer know things about your car including the condition of its bodywork, interior and exterior, engine, transmission, chassis and wheels, for example.

You’ll probably also have to send the insurer good quality photos that show the car’s exterior at different angles - its near side, far side, front and rear. Plus its interior and engine.

You may also need to attach receipts or invoices where available to show purchases and work done.

How to save money on modified car insurance

You can save money on your car insurance, even if your car’s modified:

  1. Doing low mileage and keeping your car safe in a garage or on a driveway overnight can help to bring your quote down

  2. If you pay annually, you’ll avoid paying interest on direct debit payments

  3. If you’re an inexperienced driver, adding a second driver with a safe driving history will sometimes reduce the cost – but only do this if the other person genuinely does drive your car

  4. Consider a telematics policy. Premiums are based on how safely you drive, so if you drive your modified car carefully that might reduce the cost at renewal time

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^Up to £250 refunded after claim settled. Car insurance purchases only. Excludes breakdown, windscreen and glass repair/replacement. Full T&Cs apply.

^^Based on Go.Compare analysis of successful claims, August 2019 - June 2022.

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Frequently asked questions

Yes, you need to tell your insurer about any and all modifications. That includes changes to the engine and vehicle mechanics, plus cosmetic changes. If you don’t, you risk invalidating your cover. So if you need to make a claim, your insurer could refuse to pay out.

Even things like fitting towbars, roof racks or locking wheel nuts should be declared, though they’ll probably not make a difference to premiums. If you’re in any doubt as to whether or not something counts as a ‘modification’, it’s best to tell your insurer about it to be on the safe side. 

Remember that some modifications – like fitting an immobiliser or parking sensors – could even bring your premium down.

Yes, just as you have to let your insurers know about modifications you make to a modern vehicle, the same goes for classic cars.

In fact, many classic car owners make more practical upgrades than most to their cars - things like suspension, brake and engine upgrades, power-assisted steering, electronic fuel injection and uprated radiators for improved cooling.

Not all standard insurers offer cover for classic cars, but there are plenty of specialists that do, and they’re used to covering all sorts of modifications.

If you’re a young driver, regardless of whether or not your car has any modifications, your premiums will probably be higher than for people aged over 25 anyway. That’s because young drivers are statistically more likely to claim on their insurance, so that’s taken into account when issuing a quote.

Adding modifications usually makes premiums even more expensive. For example, our data shows that, for policyholders between 17-21 years old, the average cost for comprehensive insurance for cars with modifications is £1,184. But for policyholders over 50, it’s significantly less, at just £290.[2]

If you’re looking to buy a second-hand car that differs from factory standard, make sure you’re aware of all its modifications before you buy it, so you can declare them to your insurer.

Failing to tell your insurer about any modification, whether you made it or not, can invalidate your insurance.

If you already have an insurance policy in place and then modify your vehicle, you must inform your insurer - don’t wait until you renew your policy. If you don’t declare a modification, you risk invalidating your cover.

Your insurer may charge you more, or less, for your premium because of the modification. Or it may stay the same.

A mid-term change in your policy like this may also attract an adjustment or administration fee. Your policy documents should explain if your insurer charges for making changes mid-policy.

You may want to consult your insurance provider about any modifications you’re considering before you actually go ahead and get them done, just to be sure your insurer is willing to cover the change, and whether or not it’ll hike up your premium.

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If you don’t declare all modifications, you could invalidate your policy and might not be covered

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Page last reviewed: 08 March 2023

Page reviewed by Jasmine Hembury

[2]For all comprehensive car insurance policies bought through Go.Compare in November 2022