Car valuation experts warn over modifying a vehicle - here's why

It can be tempting to modify your car – a vehicle with unique touches can reflect your taste and character almost as much as a house does.

But while it may seem like a good decision to tweak your wheels, This is Money can reveal that valuation experts are issuing new warnings to motorists to avoid doing just that.

This is because car modifications can cause resale issues as well as insurance invalidations, exclusive cap hpi research has found.

Jeremy Yea, senior valuations editor at cap hpi, says: 'The overall market appeal is significantly reduced as some modifications may appeal to niche buyers but limit the overall market for the vehicle.'

So, what's the extent of the impact on resale value and insurance, and what should you know if you are considering going ahead with mods?

Here's what the experts advise to do and what not to do when it comes to modifying your car....

Experts are warning motorists away from modifying their car because it can massively hike up insurance and end up putting a dent in the resale value 

Adding modifications can detract from the potential purchase price of vehicles because most buyers prefer unmodified cars.

Even cosmetic changes can negatively affect value, cap hpi says, with 'poorly executed paint jobs, body kits or decals significantly reducing a car's appeal and value.'

Jeremy Yea comments: 'Generally, resale values are decreased by modifications as these are typically designed to suit the taste and style requirements of the original owner.'

Engine and performance mods can be particularly problematic.

Extreme engine modifications, such as ECU remaps or larger turbos to increase the bhp output, can raise concerns about potential reliability issues and even maintenance costs.

In a similar vein, hpi warns that unauthorised or non-original aftermarket parts can reduce the vehicle's value due to potential risks and warranty issues.

Yea explains that overall, 'the effect of modifications on a car's overall value depends on numerous factors such as the quality of the work, reversibility of alterations and legality - as unapproved or illegal modifications decrease value and can make the car unroadworthy and uninsurable.'

 Fast & Furious film fans might want a car with a nitrous oxide mod like Vin Diesel, but they could end up paying a 378% premium on their insurance for that

While manufacturer modifications tend to be fine, non-manufacturer modifications can invalidate warranties and impact insurance if not fully declared.

Hpi also warns that some buyers may be unaware of modifications at the time of purchase.

In 2021, This is Money and Go Compare revealed 10 of the most expensive mods that increase insurance premiums, with Fast & Furious inspired nitrous oxide kit - which adds power to a car - topping the charts.

It added an eye-watering £2,462.64 (378 per cent hike) onto the average premium for a car with no mods.

Even cosmetic mods like side stripes can whack a 178 per cent premium onto the insurance cost of a car, the research found.

Cap hpi says to always retain original parts to potentially reverse modifications before selling

HPI says that certain procedures must be followed when modifying any car to avoid devaluing or hindering its market appeal.

Firstly, always retain original parts to potentially reverse modifications before selling.

Secondly, focus on enhancements that improve vehicle performance rather than purely cosmetic customisations.

Thirdly, ensure modifications are installed by professionals who use quality parts from reputable brands.

And lastly, consider the long-term impact on insurance and vehicle integrity – will it be worth it in the long run? Or is it just an unwise whim?

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