Modified cars may look cool, but they can also be a financial disaster

When most people picture a modified car, it’s been slammed to the ground, has a pointless spoiler stuck to the bootlid, and the engine is tuned for max power and volume. But there are lots more subtle and very much illegal modifications that can be left behind by previous owners and land unwitting buyers in a lot of trouble.

What might look like a harmless cosmetic upgrade or a subtle performance tweak could leave you facing £1,000 fines, failed MoT tests and invalid insurance. Once you buy the car, the legal responsibility rests entirely on your shoulders – whether you fitted the parts or not.

The first thing to look out for is a non- compliant number plate. From illegally spaced lettering and 3D gel fonts to dark tinted covers and illegal ‘ghost’ plates designed to evade ANPR cameras, around one in every 15 cars has a dodgy plate. While the original owner might have wanted a flashy finishing touch for their car, police and MoT testers won’t be amused.

Next up are illegal exhaust modifications. Removing silencers, catalytic converters or baffles to make a car sound meatier might satisfy a hot hatchback enthusiast, but it often pushes noise levels far beyond legal limits.

With noise-detecting cameras rolling out across the UK, an overly boisterous exhaust isn’t just an annoyance – it’s a guaranteed fine and an automatic MoT failure. 

Watch out for aftermarket LED headlight conversions and heavy window tints, too. Standard halogen housings fitted with cheap LED bulbs cause blinding glare for oncoming traffic, breaching rules.  Tinting on the front side windows that lets in less than 70 per cent of light is strictly illegal. But you need to be aware of any and all modifications that have been made not only because they can prevent a car from being road-legal, but also so that you can declare them to your insurance company.

Even if it’s just aftermarket wheels and parking sensors, a retrofitted touchscreen with Apple CarPlay, or perhaps an optional factory-fitted towbar, if you’re involved in an accident and failed to mention something beforehand, your insurer can refuse to pay out, leaving you personally liable for thousands of pounds in damages.

So before signing up to a deal, give the classified ad another read through, inspect every detail, listen closely on the test drive, and ask the owner direct questions. Even a quick visual check and some vigilance could save you a fortune.

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