Modified car insurance - Cover for your modified car

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 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. The reason you need to tell your insurer if you make any aftermarket changes is that they'll need to recalculate the insurable value of your car accordingly. This means on the one hand factoring in the added cost of replacing or repairing any modifications you've added, and on the other, re-assessing what they mean for the general risk level associated with your vehicle.

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, if your modifications only make the vehicle safer, you might see your premiums go down.

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 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.

Last reviewed: 1 February 2024

Next review: 1 March 2024