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Minor Car Modifications that Do and Don't Affect Car Insurance

Car modifications refer to any changes or additions made since the car left the factory, which doesn’t include manufacturer options that are factory-fitted. That is why we all know that kitting your car out with modifications like huge wheels, lowered suspension and a turbocharged engine will push up insurance costs.

But did you know that even minor and common car modifications can affect your premiums? Insurance companies calculate prices on perceived risk, and any modifications can increase, or decrease, your risk score. So while you may want to find a loop hole to avoid informing your insurance provider, any change you make needs to be recorded.

Insurance Risk Factors

When determining the increase in premiums, insurance companies consider three main risk factors:

  1. If the modification will raise the risk of theft by making the car more attractive to thieves
  2. If it will raise the risk of an accident occurring, such as additional power
  3. If the modification will raise the value of the car by being expensive to repair or replace

To help you confirm what and how these changes affect your insurance, here are some minor car modifications that can push your insurance premiums up or down.

Common Car Modifications that affect insurance

Before undergoing a potentially costly change, take a look at minor and major changes that affect your insurance. This handy table highlights the type of change and estimated potential increase taken from a MoneySupermarket survey.

 

Car Modification How it Affects Insurance %
Turbo/Supercharging +132%
Transmission or Gear change +63%
Complete body kit +57%
Wheel arches +41%
Roll Bars/Roll Cages +41%
Uprated brakes +36%
Replacement of seats +27%
Exhaust changes +26%
Car phone kit +26%
Air Filter +25%
Suspension +25%
Spoilers/Skirts +23%
Sunroof +17%
Tinted windows +16%
Dashboard changes +16%
LPG conversion +15%
Satellite navigation system +15%

Specialised paintwork

+15%
Air conditioning +13%
Light changes +12%
Stripes & badges +9%
Alloy wheels +8%
Tow Bars -20%
Parking sensors -13%

Naturally changes to the power/performance of the vehicle will come with the greatest premium increase, while paintwork and artwork still carry an increase.   

Minor Car Modifications

Parking Sensors

Adding parking sensors to a used car is actually a good way to drop your insurance premiums. MoneySupermarket’s data shows that installing parking sensors decrease your insurance price by an average of 13%.

Tow Bar

A tow bar is another modification that may lower your insurance costs. It can cut your premiums by 20% as it signals that the car would be travelling at slower speeds.

Tinted Windows

Tinted windows are a risky modification because they must let in at least 70% of light to be legal, otherwise they restrict your vision too much. But botched installations and DIY jobs increase the likelihood of too-dark tints. And some insurers won’t even cover a car with this modification, while others bump up prices.

Alloy Wheels

Standard alloy wheels won’t impact insurance, but if you upgrade them or even paint them a different colour, your premiums could rise. This is because better alloys may increase the likelihood of your wheels being stolen, which is a common insurance claim.

Car Seats

Modifications to interior upholstery can include upgrading to sports or leather seats. And these changes may need to be declared to your insurer, though it will vary whether they affect premiums.

Roof Rack

Research from the same survey found that adding a roof rack to your car counts as a modification, and even pushes up insurance prices by 8% on average. 

Air Conditioning

Adding an air conditioning system can add a high 13% to your insurance premiums on average.

Car Decals

This is a grey area for car insurance. Some insurers don’t care about decorative modifications, but others suggest that decals like vinyl wraps and go-faster stripes raise the risk.

A small ‘baby on board’ sticker shouldn’t be a problem, but inform your insurer about anything else. A few years ago, one insurance company tried to declare a policy invalid after finding out the car owner had stuck messages across the side panels.

And if your decals or vinyl wraps are promoting your business, make sure your car insurance covers you for commercial purposes too.

DECLARING CAR MODIFICATIONS

You must declare any moderations to your insurance company, whether they were made by you or already present when you bought the car. Sometimes modifications don’t affect the price but need to be detailed on your policy regardless.

If you don’t declare all modifications to your insurer and later need to make a claim, your policy could be declared invalid. The insurer may refuse to pay out or give you a reduced rate.

And if the cost of modifications is too high, shop around for a different insurance company – they all have a different way to calculate risk.

Thinking of buying a car? Here’s our helpful checklist of what to look for.