Modified Car Insurance

Modifying your car? Make sure you're covered.

Modifying your car? Make sure you're covered.

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There are countless ways to modify your car after you've bought it. Nicer alloys and paint jobs to make it look better, engine mods to make it go faster, or even added features to make it safer and more secure.

What all modifications have in common is that they will affect the price you pay for your insurance. Usually, this means your premiums go up but the amount it will change by can vary. We'll explain which modifications make the most difference, and how you can make sure you get a good deal regardless.

In This Guide:

What is modified car insurance?

Modified car insurance covers any changes or alterations made to your vehicle since it was purchased. This can include visual alterations as well as anything that affects the vehicle's performance. You have two options when it comes to modified car insurance. Either you can compare policies based on your currently modified car, select the right quote, and move forward.

Or, if you've already got cover but want to make further aftermarket modifications, you'll have to contact your insurer to let them know. Once you've done this, and made the modifications, they'll adjust your premiums and cover accordingly.

Types of car modification: What counts as modifying my car?

In short, anything that changes it from the state it was in when it was manufactured. This could be as drastic as changing the engine, or it could be as simple as replacing the stereo system. Anything that goes beyond standard factory specifications is a modification.

Most modifications fall into one of two categories:

Cosmetic modifications:

These are aesthetic changes like paint jobs, window tints, and anything else you can do to change how your car looks.

Performance modifications:

Performance mods improve how your car runs. This might mean tuning the engine or altering the exhaust, for example, or changing the suspension.

How do car modifications affect the cost of insurance?

Generally, a modification will increase your car insurance premiums to the extent that it makes your car more powerful (so more likely to be involved in an accident), more attractive to thieves, or more expensive/difficult to repair.

Here's a rundown of some popular modifications and the effect they'll have on your insurance premium:

Window tints

Tinted windows can make your car safer - they can make it harder for thieves to look inside and see any valuables, and the plastic film can stop glass from shattering into the car in the event of an accident. 

As with any modification, the fact that they would have to be repaired in the event of an accident means an added cost to the insurer, but they are unlikely to dramatically increase our premiums.


Spoilers do have some effect on the performance of a car but not as much as many might think. Especially if you're driving in a city, a spoiler is primarily an aesthetic change.

Your premiums will go up a fair bit if you install a spoiler, however, as it can mean a not inconsiderable extra cost in the event of any necessary repairs.

Bodywork customisation

Any major changes to the bodywork of your car will significantly increase the cost of your insurance. Custom parts are much harder to track down in case repairs are needed, and depending on the modification you may need a specialist garage.

Tow bars and roof racks

Roof racks and tow bars are often considered accessories rather than modifications, but it's still a good idea to inform your insurance company if you install either when you're going away, for example. Your premiums probably won't change though.

Audio systems

Upgrading your car's stereo system will make it more attractive to thieves (if it's visibly obvious), as well as add to repair/replacement expenses. You'll see your premiums go up a fair bit if you add a new audio system.

Breaks and suspension

Depending on which way you go with these, your premiums might go up or down. Strong breaks and tighter suspension can make your car safer and more durable, but softening your suspension or lowering the car can do the opposite.

Alloy wheels

It's hard to find a car these days that doesn't have alloy wheels as standard, but people still often want to upgrade to bigger or better alloys. Unsurprisingly, the bigger and better, the more your premiums will go up.

What does modified car insurance cover?

Modified car insurance policies are much the same as any standard car insurance policy, with the added benefit of accounting for the unique modifications made to your vehicle. The extent of coverage largely depends on the type of policy you select:

Third-Party Only Policy:

This basic level of insurance covers you for any claims made against you by others for bodily injury or property damage. It is the minimum coverage required by law but does not cover any damage to your own vehicle.

Comprehensive Policy:

A comprehensive policy includes everything a third-party policy does, plus coverage for damage to your own vehicle. This is the most extensive form of car insurance and is recommended for modified vehicles due to the higher values often involved.

In addition to the standard coverage, modified car insurance policies typically consider the value of your vehicle's modifications when settling claims, provided these modifications were declared when the policy was taken out. Depending on the policy you choose, you might also be covered for:

  • Theft of Personal Possessions: Coverage for items stolen from your car.
  • Personal Accident Cover: Compensation for injuries to the driver and passengers as a result of an accident.
  • Additional Named Drivers: Coverage for other drivers named on your policy to drive your modified vehicle.
  • Misfuelling: Protection in case you accidentally fill your car with the wrong type of fuel.
  • Cover to Drive Other Cars: Allows you to drive other cars with the owner's permission, under your insurance.
  • Courtesy Car: Provides you with a car to use while yours is being repaired under a claim.
  • Driving Abroad: Extends your coverage to when you are driving in foreign countries.
  • Windscreen Cover: Covers the cost of repairing or replacing your car's windscreen if it gets damaged.

What does modified car insurance not cover?

Understanding what's not covered by your modified car insurance is as crucial as knowing what is. Certain modifications can invalidate your policy, especially if they don't comply with legal standards. Here's a rundown of modifications that generally aren't covered because they either breach legal regulations or significantly alter the vehicle's original specifications:

  • Excessive Window Tinting: There are strict legal requirements for window tinting. The law requires that the front windscreen and front side windows must allow a minimum of 75% and 70% of light through, respectively. Modifications that darken windows beyond these limits are not covered.
  • Non-Standard Headlight Colours: According to the Road Vehicles Lighting Regulations 1989, front vehicle lights must emit a white or yellow light, and rear lights must be red. Any modification that changes these colours, or significantly dims the light's intensity, is not usually covered. This includes the application of films or covers that alter the colour or intensity of the headlights.
  • Nitrous Oxide Systems: Although not outright illegal, nitrous oxide systems for boosting engine performance are considered high-risk by most insurers. Due to the potential for increased engine wear and the heightened risk of accidents, modifications involving nitrous oxide systems are usually excluded from coverage.
  • Unsafe Spoilers: While spoilers themselves are not illegal, they must be installed safely and securely. Spoilers that are not properly fitted, have sharp protruding edges, or obstruct the driver's rear view could be deemed unsafe and are not covered. Such modifications could also attract penalties from law enforcement.
  • LED Headlight Conversions: Replacing halogen headlamps with LED bulbs in vehicles not originally equipped with them is often not covered. This is because conversion kits can alter the lighting system in ways that were not intended by the vehicle manufacturer. Vehicles designed with LED headlights from the factory are an exception, and like-for-like replacements are typically covered.
  • Loud Exhaust Systems: Modifying your exhaust system to increase noise levels can lead to non-coverage. Legal guidelines stipulate that new vehicles must have exhaust systems emitting noise below 72 decibels. Alterations that amplify noise beyond this threshold are typically excluded.

Does it always cost more to insure a modified car?

Generally speaking, yes, simply because custom parts are harder to source than factory standard parts. However, it's a common misconception that all modifications will automatically lead to higher premiums. In reality, the effect of modifications on insurance costs is relatively complex, with certain changes potentially lowering your rates. For example:

Security Enhancements:

Adding security features such as advanced alarm systems, immobilisers, or vehicle trackers can actually reduce your insurance premiums. These modifications decrease the likelihood of theft, making your car a lower risk for insurers. Surprisingly, even something as simple as installing a towbar has been known to reduce insurance quotes, possibly because it suggests a lifestyle that involves less risky driving behaviour.

Safety Improvements:

Similarly, modifications aimed at increasing safety, such as better brakes, additional airbags, or improved lighting, can also be viewed favourably by insurance companies. These enhancements can reduce the likelihood of accidents, potentially leading to lower premiums.

However, it's important to recognise that many modifications can increase your insurance costs. This is because they can:

  • Increase the Vehicle's Value: Custom parts and unique modifications can significantly increase the overall value of your vehicle, which in turn can raise the cost of insurance.
  • Elevate Repair Costs: Modified vehicles often require special parts for repairs, which can be more expensive than standard vehicles.
  • Heighten Accident Risk: Certain performance modifications, such as engine tuning or suspension changes, can make a vehicle more powerful or alter its handling characteristics, potentially increasing the risk of an accident.

Attract Unwanted Attention: Modifications that enhance a vehicle's appearance or performance can also make it a more attractive target for theft or vandalism.

Always tell your insurer about any modifications

If you are planning on making any modifications to your car, you should always get in touch with your insurer to find out how the price of your premiums will change.

It is imperative that you inform your provider about any changes you decide to make, as if you are caught out with any undeclared modifications, you could invalidate your policy and stop any payouts.

How can I get cheaper insurance on my modified car?

While your premiums will go up if you've tuned up your car, this doesn't mean you have to pay over the odds. There are various ways to save money, including keeping your newly modified car in a garage instead of on the side of the road. You could also consider adding a named driver to your policy, or having a black box installed in order to cut down the cost of your premiums.

Find a modified car insurance policy

Insuring modified cars can be more difficult than securing cover for a standard vehicle, but it doesn't have to be. Get in touch with our team for a cheap modified car insurance quote, or request more information about the types of policies that are available.

Last reviewed: 1 June 2024

Next review: 1 July 2024