Over 1.5 million UK motorists could be unknowingly operating with invalid insurance due to having modifications they might not have declared.
A survey of 2,000 UK drivers by Tempcover found that one in four vehicles on the road have at least one non-factory modification.
However, confusion around what constitutes a ‘modification’ means that 14% of drivers with altered vehicles could face reduced claim payouts.
Additionally, depending on the severity of the undeclared change, drivers could face cancelled cover in the event of a collision.
Top 10 car modifications motorists don't know they are required to declare
Google Trends data indicates UK search interest in 'wireless CarPlay adapter' surged from 2024 onwards, hitting an all-time high within the past 12 months.
Despite their popularity, many motorists are unaware that installing these devices may affect their insurance.
According to Tempcover, 91% of drivers do not realise that retrofitting aftermarket infotainment units such as Apple CarPlay or Android Auto must be declared.
Similarly, 88% are unaware that upgrading a car’s speaker system requires disclosure, and 77% do not know that non-factory alloy wheels and custom paint also need to be reported.
Tempcover's research found the top 10 undeclared car modifications are:
- Unofficial Apple CarPlay, Android Auto, or touchscreen retrofits – 91%
- Non-factory parking sensors – 88%
- Upgraded sound system or speaker installations – 88%
- Retrofitted parking sensors – 87%
- Paint protection film (PPF), vinyl wraps, or body stickers/decals – 86%
- Installed towbars or roof racks – 86%
- Bulb replacement with brighter aftermarket lights – 82%
- Aftermarket alarms, immobilisers, or GPS trackers – 78%
- Non-factory alloy wheels, custom paint, or tinted windows – 77%
- Engine ECU remapping, chip tuning, or pedal boxes – 72%
Claire Wills-McKissick, temporary car insurance expert at Tempcover, said: "When adding plug-and-play tech or modernising a car, many motorists may not think twice about insurance.
"But omitting material vehicle changes – even accidentally – can be treated as careless misrepresentation, or more seriously, insurance fraud if the concealment is deliberate.
"Insurers calculate premiums based on risk, and this includes temporary cover too.
"Adding an aftermarket infotainment system alters the vehicle’s value and can increase its theft risk.
"These are material facts an insurer needs to know when deciding whether – and on what terms – to offer cover."
Insurance fraud can see your insurance cancelled, as well as potential fines and penalty points depending on the severity of the case.
Wills-McKissick recommends motorists check their vehicle handbook, review their policy terms, and confirm directly with their insurer if they're unsure.
What car modifications are illegal in the UK?
Halfords shares that there are a number of illegal car modifications in the UK, including tinted windows, neon lights and loud exhausts.
Number plates are also a common illegal modification, as the retailer said: "Custom number plates that don’t meet the DVLA standards in terms of size, spacing, and reflectiveness can result in fines."
Meanwhile, having a spoiler that isn’t safely fastened to the car can land drivers in trouble with the police.
Car modification risk in second-hand vehicles
Car modifications could also have risks further down the line, due to drivers potentially discovering them only after completing a used car purchase.
Michael Golson, motoring expert at Cazoo, said: “The biggest issue with many modifications is that a used car can look completely standard while hiding changes that affect its performance, reliability or insurance.
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"Buyers shouldn’t be afraid to ask direct questions about remapping, gearbox software and whether the car has ever been modified and then returned to standard.
"A little extra scrutiny before buying could save you from an expensive surprise further down the road.
"The big risk is the cost of reversing it, as replacing tampered emissions equipment can easily run into four figures - with a replacement DPF costing around £1,000 to £3,500.”
Have you made any modifications to your car? Let us know in the comments.
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