Brits warned that their car insurance could be invalid without realising

A warning has been issued to thousands of British motorists explaining that their car insurance could be invalid without them even knowing.

After passing your driving test and finally getting your licence, car insurance is one of those absolute necessities when it comes to taking to the open roads by yourself.

Alongside taxing your motor, you need to pay for insurance in case you have an incident while out and about. Ultimately, it gives you financial protection should you unfortunately be involved in an accident.

Regardless of what kind of cover you get - fully comprehensive; third party; or third party, fire and theft - it is illegal to not have it. But thousands of motorists who have insurance policies could be in for a shock should they need to claim after suffering a collision.

Car insurance warning

A warning has been issued by the Financial Ombudsman Service (FOS) to thousands, with even the smallest change to your car meaning your insurance could be 'wrecked'.

The warning concerns car modifications, which range from simply tinting your windows to getting a brand-new super-powered engine.

Modifying your vehicle could leave you thousands of pounds out of pocket, basically.

That's because when you make a modification to your vehicle, this should be updated on your car insurance policy, but the problem is that many people don't realise this.

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

Written off (Peter Dazeley/Getty Images)

What the car insurance warning actually means in reality

The Financial Ombudsman, which is an independent service set up to resolve disputes between consumers and financial firms, sees cases where a failure to declare these modifications leads to insurance being invalidated or claims being rejected in the event of an accident.

Often drivers are not aware that modifications – even seemingly minor alterations such as tinted windows or stereo system enhancements – can lead to higher premiums due to the increased risk associated with those vehicles.

Rachel Lam, Ombudsman Director of Insurance at the Financial Ombudsman Service, said: "For many people a car is their pride and joy, and it’s understandable that they may want to modify or personalise their vehicle.

"But these changes can have huge repercussions – increasing premiums, invalidating insurance, or leaving unsuspecting car owners thousands of pounds worse off.

"It’s crucial owners inform insurers of any modifications, even if they were made before the car was purchased.

"If people don’t feel they have been treated fairly by their insurer, they can come to our service, and we will investigate their complaint. Getting a fair answer is free and easy."

Your car doesn't need to be written off to make a car insurance claim worth it (Getty Stock Images)

What counts as modifying your car?

According to Auto Trader, there are two forms of car modification: cosmetic and performance.

Changes made to the vehicle's look are classified under cosmetic modifications. Cosmetic modifications include a new body kit; front and rear bumpers; rooftop vents; a new paintwork; wheel accessories; interior LED lighting; light lens tints; tinted windscreens; back bumper reflector lights; custom hood ornaments; and dashboard customisation.

Performance changes change how the car performs on the road. This concerns changes to the car in the realm of new brakes; a new engine and drivetrain; new exhaust; new suspension; new steering system; and a new filtration.