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Modified car insurance

From alloys to spoilers, car modifications tend to push your car insurance prices up. But in some cases, such as with security features, they could lower the cost.

A red modified car infront of a wall of graphiti

Here we look at everything you need to know about car modifications. 

What’s classed as a car modification?

Anything that changes your car from the point at which the manufacturer sends it off the production line is a modification.  

This could be anything from a roof rack to tinted windows. Your car insurer could charge you extra if your car has been modified.

Insurers usually have a list of modifications they automatically cover and a list of those they might charge you more for. But this depends on the insurer and the car insurance policy. 

You could also buy a specialist insurance policy for modified cars, depending on the type of car you have.

Types of car modifications

There are lots of different types of modifications and car insurance add-ons you need to be aware of. They could add to the cost of your car insurance policy, or could mean you need a specialist insurer.

Most common modifications tend to be covered by standard insurers, although they’ll usually want to know about them. 

Modifications are usually classed as either performance or cosmetic. Performance modifications are those which  - as the name suggests - affect your car’s performance.

This could be changing the wheels, tweaks to the engine or turbo upgrades, for example.

Cosmetic modifications on the other hand are all about how the car looks. These could include tinted windows, fitting a sunroof, or specialised paintwork. 

Here we look at some of the most popular.

Bodywork modifications

Body kits can be added onto the existing body work of a car or replace it entirely.

They might change how it looks and also how safe it is. These include:

  • Spoilers
  • Bigger bumpers
  • Front and side skirts
  • Wheel arches
  • Flared wings
  • Valances.

Brakes and suspension modifications

Changing or upgrading the brakes or suspension (or both) could impact how a car drives.

Whether it’s improving your brakes to make you stop faster or replacing worn out bushings in your suspension. 

Cosmetic modifications 

There’s no end of options when it comes to cosmetic changes. The most common are:

  • Tinted windows
  • Vinyl wrapping
  • Custom paint spray to change the colour and look of the car.

Engine modifications

Anything that changes the way the engine works counts as an engine modification.

Changing the engine could impact how a car drives, making it faster and giving it more power. As this could be a major change, most insurers will need to know about the modification.

Tow bars, roof racks and immobilisers

External changes such as adding a roof rack or tow bar may not seem to make a big difference. But they could affect the size of a car and how aerodynamic it is. 

Audio systems 

Making a change to the audio or entertainment system of a car could increase its value.

An insurer might need to know about this as it could affect the overall risk of the car being stolen and the cost of repairing or replacing it.


It’s not always boy racers who go for spoilers. But generally they’re used for making a car go faster and could increase the risk of breaking the speed limit. 

Does it cost more to insure a modified car?

Lots of different factors affect how much you pay for car insurance including:

  • The age and model of the car
  • The address and profession of the main driver.

When it comes to modifications, you could buy specialised insurance to cover these or you could add them onto a standard policy. 

Usually, modifications add more to the cost of the policy.

So, it’s worth shopping around and comparing the cost of modified car insurance before you buy. Or speak to your existing insurer to find out how much it might charge you. 

If you add the modification you could also be charged if you need to change your car insurance policy. This is because some insurers charge an administration fee if they need to recalculate a policy. 

Compare car insurance quotes

What modifications are likely to affect the cost of your insurance?

Not all modifications are seen equally by an insurer. So, if you’re thinking of modifying your car, it might be worth calling your insurer first, or speaking to a specialist insurer.

They should be able to let you know how much your insurance could change when you’ve had the modification.

Modifications, especially cosmetic ones like tinted windows or customised paint, sometimes increase the car’s value.

This could make it more attractive to thieves, or increase the cost of making repairs - especially if the modification is something unique. 

Some modifications might also dramatically change the way a car drives, and this could increase the risk of an accident and making an insurance claim.

If you buy a specialist policy for modified cars you could choose to have an agreed-value policy. This pays out a set value for your car rather than the market average.

You could also add a salvage retention clause that allows you to buy back the remains of your car if it’s a write off.

How to cut the cost of modified car insurance

Modified car insurance can seem expensive but there are many ways to cut the costs of your car insurance policy:

Safe storage

If your modified car is out on the street for anyone to see, there’s a higher chance of it getting stolen.

Store it safely outside, ideally in a locked unit or garage, and you could see your car insurance fall.

Pay annually

Paying monthly for car insurance is usually more expensive than making one annual payment. This is because interest is added to the monthly amount. If you can, pay it all in one go. 

Add a second driver  

Younger drivers, or those with little driving experience, tend to pay the highest amounts for car insurance.

If you can add a second driver to your policy who has more experience, such as a parent of a young driver, this could lower the overall cost.

But there are no guarantees. Also, the other driver can’t be put as the main driver of the car unless this is true - as this is known as fronting and is illegal.

Lower your mileage

The more miles you rack up, the higher the chance of having an accident and needing to repair your car.

If you can keep your mileage down this could lower the cost of your insurance. 


Consider black box technology

Telematics, or black box technology, monitors the way you drive. If you drive consistently well, it could lower the cost of your insurance premium.

Are there any car modifications that don’t affect my insurance cost?

Not every car modification will necessarily increase your premiums and in some cases they could even lower them.

External modifications such as tow bars and roof racks are less likely to make too much difference to how you drive your car. That’s as long as they’re fitted properly.

So,  they might not push up your insurance, but you do need to tell your insurer if you make a change like this.

Some car safety add-ons, such as immobilers, trackers, or alarms might also lower your premiums. 

If a modification improves your car security and makes it harder to steal, it could make your car insurance cheaper.

This all depends on the insurer though, so always double check before making a modification.

Is a towbar classed as a modification? 

A towbar is something you’re changing about your car and therefore it’s classed as a modification. 

But it’s not likely to change your car’s performance, or the likelihood of it getting stolen. So it might not make a big impact to your premium.

If you want to know more check out our guide on towing rules and insurance.

Do tinted windows affect car insurance?  

If you want to tint your windows, it’s worth checking with your insurer first. It’s up to them how they change your car insurance policy.

The UK government laws for tinted windscreens state that there are no rules for tinting the rear windscreen or rear passenger windows. 

If the vehicle was first used on 1 April 1985 or later, the front windscreen must let at least 75% of light through. Also, the front side windows must let at least 70% of light through.

If the car was first used before this date,  the front windscreen and front side windows must both let at least 70% of light through.