Car modifications and insurance

Date published: 1 October 2024 Motor Insurance : Category Insurance : Category

Modifications to your car can affect your insurance, whether it’s adding tinted windows, changing the alloy wheels or upgrading the exhaust system.

Here, we share information about how car modifications can affect insurance policies, the types of complaint we’ve seen and how we can help. 

What is car modification?

Car modification involves making changes to your car that are not part of the manufacturer’s standard specification.

Modifications cover a range of things. It can include simple things like changing alloy wheels or adding tinted windows, or more complex changes, such as upgrading exhaust system or engine tuning. 

We’re seeing cases where car owners had to pay a significant amount of money because they unknowingly invalidated their insurance after modifying their car.

We’ve also seen cases where car owners told their insurer about the modifications and paid more for their insurance. But when they made a claim, they discovered that the value of the modification isn’t covered.

Here, we share information about how modifications can affect your car insurance, some tips to look out for from the cases we've seen and how we can help if you have a complaint. 

How can modifications affect your insurance?

Whether it’s changing alloy wheels for extra style or remapping the Electronic Control Unit (ECU) for better engine performance, not declaring these modifications to your insurer can have serious consequences.

Often, drivers are unaware that simple modifications, like tinted windows or changing alloy wheels, can lead to higher premiums due to the increased risk associated with those vehicles.

There are usually specific terms or conditions you need to follow if you want to modify a vehicle, to make sure your insurance cover remains valid.

Whatever changes you’re considering making to your car, it’s important that you inform your insurer as soon as possible.

If you make a claim without notifying your insurer about any significant changes, your policy may be invalid because the insurer might say that the modifications mean that:

  • your vehicle is at a higher risk of being stolen
  • they would have increased your premium if they’d known about the modification
  • they wouldn’t have continued to provide cover for your car if they had known about the modification

Want to modify your car?

If youre looking to modify your car, you should:


Check your policy

Before making any modifications, check your insurance policy and contact your insurer to clarify what needs to be declared.

Understand before you buy

If you buy a vehicle ask questions and examine paperwork to understand if it has previously been modified.

Be honest and transparent

Always provide accurate information about any changes to your vehicle when applying or renewing your insurance.

Seek advice

If you are unsure whether a modification could affect your insurance, it is always best to ask your insurer.

How we can help

We hear from people who tell us they’re unhappy because they had problems with their claims or that the insurer unfairly voided their policy. 

If you feel you’ve been treated unfairly, you should complain to the insurer first. If you’re still unhappy and want to take your complaint further, we may be able to help. Our service is free and easy to use. 

When we investigate a complaint about this, we’ll check what the policy says and what type of cover is offered. We’ll look at the policy wording to decide if you’ve been treated unfairly.

However, if you haven’t told your insurer about any significant modifications you’ve made and it’s clear in the policy that you should have done so, then it’s unlikely we’ll uphold your complaint. 

Examples of cases we see and resolved

  • A consumer came to us when his insurer voided his motor insurance policy and refused to pay after his car was stolen.

    He didn’t tell them about modifications made to the vehicle when he took out the policy, even though he was asked for this information – the modifications were only discovered when the insurer started looking into the claim.

    Had they been told about the modifications earlier, they wouldn’t have sold him the policy. We agreed that the insurer was within its rights to void the policy and refuse all claims.  

  • A consumer came to us after his motor insurer voided his policy and declined his claim following an accident.

    When the insurer looked at the claim, they discovered the car had alloy wheels fitted that were three inches larger that the manufacturer’s standard size. The consumer claimed he did not know the wheels had been modified.

    We felt that an average consumer would not spot the difference in the new and standard tyres. For that reason, he believed the consumer took reasonable care when applying for motor insurance. As a result, the insurer was ordered to reinstate the policy and take several other steps to put things right, including compensating the consumer for distress and inconvenience.

  • In another case, a consumer made a claim after an accident, only to have his policy voided when the insurer learned about an undeclared ECU remap and exhaust retuning. The consumer argued that these modifications were already in place when he purchased the car.

    Despite this, the insurer produced evidence that he was aware of the modifications and had failed to disclose them. We agreed that the insurer’s decision to void the policy was fair and in line with legislation.

  • A consumer came to us  after his insurer voided his motor insurance policy and refused to pay his claim. They said he had changed the air filter of his car and considered that change to be a modification (and performance enhancing), which the consumer should have told them about.

    After investigating the case, we didn’t think the consumer made any misrepresentation to insurer and didn’t think he should reasonably have considered that changing the air filter amounted to a modification for the purposes of the policy. We also felt that the replacement air filter had a negligible impact on the performance of the car – and on the likelihood of it being stolen or damaged.

    The insurer was ordered to reinstate the policy, settle the claim, and pay compensation for the trouble and upset caused. 

Bringing your complaint to us

Getting a fair answer is free and easy. 

When you bring a complaint to us, it’s our job to weigh up all the facts. We’ll make a decision about what happened using evidence from you, the insurer and any relevant third parties. We'll also consider:

  • the relevant law
  • any regulations that applied at the time
  • any industry codes of conduct that were in force at the time

When we’ve finished investigating, we’ll tell you whether we think the insurer treated you fairly or not. And we’ll explain how we reached our decision.

If we think the insurer treated you unfairly, we’ll tell them to put you back where you’d be if they hadn’t made a mistake. We might also ask them to make an award for any distress and inconvenience caused.

Bring your complaint to us