Modifications that Make a Car Uninsurable
Custom changes to your car can exclude it from cover automatically - our list of common enhancements is published to help you know if you're insured or uninsured.
Updated 12 December 2024
Car insurers don't like risks, and for this reason, they limit their exposure to cars (and drivers) who are more likely to claim. Unknown to many New Zealanders, there are many modifications you can make on a vehicle that will exclude the car from being insured. Our list below covers 10+ such modifications or enhancements that prevent you from getting a policy from most insurers.
Top Tip: If you have modified your car or are planning to, check your policy - not all insurers are the same, but many have similar exclusions. By reading the fine print (or calling your insurer), you will prevent a situation of unknowingly driving uninsured.
Further Car Insurance information
Video guidance: MoneyHub Founder Christopher Walsh explains the hidden risks of car modifications (and how they void car insurance policies) in the video below:
Car insurers don't like risks, and for this reason, they limit their exposure to cars (and drivers) who are more likely to claim. Unknown to many New Zealanders, there are many modifications you can make on a vehicle that will exclude the car from being insured. Our list below covers 10+ such modifications or enhancements that prevent you from getting a policy from most insurers.
Top Tip: If you have modified your car or are planning to, check your policy - not all insurers are the same, but many have similar exclusions. By reading the fine print (or calling your insurer), you will prevent a situation of unknowingly driving uninsured.
Further Car Insurance information
- Want to know more about car insurance? Our Car Insurance guide has you covered
- Want to compare the major policies? Visit our AMI vs AA Insurance vs Cove vs State vs Tower vs Trade Me Insurance guide.
Video guidance: MoneyHub Founder Christopher Walsh explains the hidden risks of car modifications (and how they void car insurance policies) in the video below:
Boost ControllerWhat is a Boost Controller?
A boost controller is exactly what it says. The boost, which could be turbocharged or supercharged, is controlled by the controller. You can only install the boost controller if there is some type of boost in your car. How it Works A Boost Controller essential to any form of turbo in the car, as the boost controller keeps track of how much air pressure can travel to the mechanical wastegate actuator. The higher the air pressure travelling to wastegate, the higher the boost. Insurance Issues Many insurers won't cover a car if it has a Boost Controller. The boost controller is usually included in the turbochargers, but it can be installed as an aftermarket feature. If your car has a Boost Controller, check your policy will cover your car. |
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Internal Engine ModificationsWhat are Internal Engine Modifications?
There are multiple internal engine modifications, from oil changes to ignition changes, to larger injectors to better compression. All such modifications increase the performance of a car. How They Work Engine modifications are made to reduce friction in the engine and keep it as smooth and powerful as possible. You can install low friction items in your engine, such as:
Insurance Issues Modified engines and car insurance do not mix given the increased risk of an accident. For this reason, they're uninsurable under many policies. |
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Modified Engine Management SystemsHow They Work
There are a few aspects to increasing engine performance and power in any car. A Modified Engine Management System measures how fuel injection and throttle body work, adding extra power to an engine. They also maximize the productivity of turbochargers, superchargers, high compression ratios, or any other boost method. Insurance Issues Modified Engine Management Systems are only installed in modified cars, which are always a higher risk to an insurer. For this reason, any vehicle with such a system will usually be excluded from cover. |
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​Aftermarket Fitted Turbo/SuperchargerWhat is an Aftermarket Fitted Turbo/Supercharger?
Aftermarket fitted turbochargers or superchargers are among the most popular items in demand amongst owners who modify their cars. Both superchargers and turbochargers work by pushing extra air into the engine to increase performance. More air entering the engine translates into more performance. It is usually used to increase the power of any engine but can also increase efficiency. How They Work Turbochargers and superchargers are the reason why smaller engines are becoming more common and conventional engines are declining. The boosted engines can produce the same amount of power while housing a much smaller engine, which is why every performance enthusiast wants a turbocharged car. Insurance Issues Turbocharged and supercharged cars and insurers do not mix well, and for this reason, many policies exclude them altogether. If your car has either modification fitted, check your policy to see if it's covered. |
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​Carbon Fibre PanelsWhat are Carbon Fibre Panels?
Carbon fibre panels counteract weight, as weight is inversely proportional to the performance of any car. More weight means less performance. How They Work While manufacturers do their best to keep the cars as lightweight as possible, carbon fibre panels are the lightest material for cars. They replace the standard panelling and reduce the weight of your car. People usually install carbon fibre panels alongside turbochargers as both items increase the performance of the cars. Insurance Issues Car fibre panelling is attractive to thieves who can re-sell the pieces or steal the car outright. As such, the higher risk makes them insurable in many policies. |
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​Door ModificationsWhat are Door Modifications?
Door modifications range from completely changing the doors outright, changing how they open, installing different features in the door, and/or making them lightweight. How They Work Door modifications have two types of changes available:
Insurance Issues Door modifications are more desirable to thieves, which makes the entire car uninsurable in many policies. |
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​External WastegateWhat is a Wastgate?
A wastegate is a valve or a pipe that controls how much air or any other gas can travel to the turbine wheel, which then translates to more or less power depending on how much exhaust gas (air, or otherwise) is regulated to the turbine wheel. How They Work External wastegates are wastegates installed outside the turbochargers. This specific type of wastegate is a more enthusiast-level item. They can help control the boost more specifically than internal wastegates, especially in engines with larger turbochargers aiming to achieve even higher performance. Insurance Issues External wastegates make cars more attractive to thieves and for this reason alone cause the car to be uninsurable with many providers. |
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​Fuel Modifications (other than petrol, diesel, or LPG)How They Work
The most common fuel types other than the conventional ones are Ethanol, Hydrogen-based engines, CNG, and Electric. Compressed Natural Gas (CNG) uses the gas supplied to homes for cooking and other purposes in the car to power it. Ethanol-based engines are incredibly rare, for they are less efficient than typical petrol engines, and they also have lower performance. It is usually used in combination with petrol engines by arranging it in a 10%/90% way to petrol, or 15%/85%. Insurance Issues Cars with modified fuel sources are a higher risk to insure for many reasons, and for this reason, are usually excluded from standard policies. |
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​Gearbox UpgradeWhat is a Gearbox Upgrade?
Gearboxes are essential to how the car would perform. They are responsible for putting the power from the engine down to the car. Cars with turbochargers doubling the original power need a compatible gearbox that will not bottleneck the engine. How They Work For example, if you have a 4-speed gearbox with a high-powered engine such as 500 horsepower, it would bottleneck as the gearbox cannot provide power quickly enough for the car to accelerate. To ensure that doesn't happen, gearbox upgrades are required in which the gearbox is either modified or changed entirely. Insurance Issues Modified gearboxes are associated with street racing and, generally, make insuring such a car very high risk. For this reason, insurers usually exclude cars with this modification. |
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Roll CageRoll cages are mainly used to keep the passengers and the driver of the car safe in case of an accident or problem. To prevent passengers and the driver from facing fatal injuries in case of a rollover, roll cages are installed in cars.
But that is not their only use. They are also used to reduce the weight of a car aims for extra high performance. Roll cages are installed by taking out the seats that the owner does not need and installing a carbon fibre roll cage or any other lightweight material to lower the car's weight. Insurance Issues Roll cages imply a car is used for racing, and in almost all cases, will be uninsurable. |
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Racing HarnessA racing harness is a type of unique safety seat belts installed in race cars and high-performance cars. This racecar-specific seat belt will help protect the people in the car in the event of an accident.
Insurance Issues Racing harnesses attract thieves and imply a car is used for racing, and in almost all cases, will be uninsurable. |
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Specialized Paint, Paint Effects and InteriorsSpecialized paint or paint effects are popular, as are specialized or customized interiors, which usually include:
Insurance Issues Cars with specialist paint effects and/or interiors are more attractive to thieves and usually won't be covered by a standard policy. |
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Suspension ChangesWhat are Suspension Changes?
Modification in the car's suspension helps in both the car's appearance and performance and the ride itself. Usually, the job of the suspension is to keep the car as smooth and above the road as possible, managing road grip, bumps, height, and any other relevant metric. How it Works Racing cars and high-performance cars usually go through suspension modifications to lower them to increase road grip and provide better stability at high speeds, improving the vehicle's aerodynamics. Lowered suspension makes the ride a little bumpier but adds personality to the car. Insurance Issues Lowered cars are higher insurance risk due to the assumption they will be street raced. For this reason, cars with suspension changes are usually excluded from cover under a policy. |
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Understanding What Your Car Insurance Doesn't Cover
Beyond modifications, it's useful to understand and be aware of what general exclusions apply to car insurance policies. To help you understand your policy's fine print and terms, our video below explains the common exclusions:
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