There is a reason why car manufacturers make cars the way they do: they want each model to appeal to the widest possible audience. Many car enthusiasts are keen to drive a car that’s tailored to their particular set of preferences, whether they be visual or performance-related. But every modification comes with a compromise, and sometimes that compromise can affect your insurance premium.
Why declare my modifications?
If your car has been modified, you must declare this – even if you have not made the changes yourself – or your insurance could be invalidated. It is also important to update your insurance company as and when you make additional modifications, so you remain covered.
As the policyholder, the responsibility is on you to declare all modifications. If you’re buying a car second-hand and are in any doubt of work that may have been carried out, get the car checked by a mechanic. If you don’t declare the modifications – regardless of whether the omission was intentional – your claim may be refused, and your insurance will be void.
If you have insurance refused or cancelled, you will find it harder and more expensive to get cover in the future. So, if you’re in any doubt, double-check and declare.
This article will detail a number of modifications and their effect on your insurance premium. It will also give you an idea of what you need to declare.
Modified vehicle: a definition
A modified vehicle is one that includes anything that has been altered from factory standard, or since it has left the factory. This can range from the small to the large, from a new engine to a small bumper sticker.
This section covers modifications to the engine or vehicle mechanics, such as the exhaust system, transmission, or air filter. These mods can improve your vehicle’s performance, but in 70-80% of cases where the engine size is increased, you’ll also see an increase on your premium. If you stick to a similar engine size, your premium is less likely to be affected.
If you have an old auto with a large engine size, for example an old Land Rover, then installing a smaller engine may reduce your insurance costs due to improved fuel efficiency.
One example of such a modification is the installation of an Engine Control Unit (ECU). All cars are set up at the factory to control the fuel-air mixture in the engine, which maximizes efficiency and power. Many manufacturers program the ECU’s parameters far below the car’s capability. Reprogramming, or ‘remapping’, this can improve engine performance and, in some instances, return better gas mileage. Adding or replacing the ECU’s chip to make the car more economical will increase the brake force power of the vehicle slightly. This may increase your premium, but only up to about 5%.
However, remapping the ECU to get substantially higher performance from your engine could cost more. As a general rule of thumb, the percentage increase to your premium will be about the same as the percentage increase in horse power.
Another example is the installation of a cold-air intake outside the vehicle. This not only frees up the air flow to an engine, it also feeds it cooler, more condensed air. Cooler air is denser and brings more oxygen into the combustion chamber, and that means more power. These modifications will have less effect on your premium than remapping your engine.
Many drivers relieve pressure on the engine – and return a little bump in horsepower – by improving the exhaust system, which aids waste flowing through the engine. This usually means making the exhaust bigger and louder. Note that many ‘big bore’ exhausts are illegal, due to the amount of noise they make (usually because the exhaust silencers are removed.)
If your exhaust system is illegal, you could face an on-the-spot fine, and your car may be taken off the road until it’s returned to legal standards. And of course, illegal additions to your car will invalidate your insurance policy.
Body kits are often added onto existing bodywork, or replace current bodywork, resulting in the safety of the car being compromised. For example: adding a bigger bumper to make it look unique or sporty. But bumpers are made with safety in mind, while body kits are not necessarily made to meet the safety standards required – sometimes crumbling under the tiniest of impacts.
Mods such as front and side skirts mean less ground clearance, and this can be hazardous on uneven roads. Most body kits tend to be made of fibreglass or polyurethane which makes them more likely to splinter in the event of a crash.
Body kits may conjure images of young men racing their friends, but there are also plenty of 50-70-year olds who are keen on these types of modifications! In general, if you have a standard policy, bodywork changes can increase your premium by 10-15%. However, if you already have a modified insurance policy, a body kit is unlikely to affect your premium unless it dramatically increases the value of your car.
The following cosmetic modifications can affect your car insurance in similar ways:
- Flared wings
- Wheel arches
A popular body kit modification for Toyota MR2 owners is to transform their cars into Ferrari replicas. In cases such as these, the type of insurance policy you’re under may change. It’s always best to check with your insurance company before doing any work.
If your car has been fitted with uprated brakes, its behaviour on the road will be altered. Sports drivers, for example, will install high-temperature brake pads and fluid to get shorter, more consistent stops out of their brakes.
It is possible to install high-performance brakes into certain non-sports cars. If your car is already highly modified, an improved braking system may reduce your premium as much as 10-15%. If your car isn’t modified, or only has a few modifications like alloy wheels or suspension, your premium is unlikely to be affected. This is because most cars are factory-fitted with suitable brakes already.
It is possible to install carbon-ceramic discs and drilled or slotted discs (which allows for faster cooling as air passes through the holes.) These can be worth a lot of money, and may increase your premium as a consequence of your increase car value.
Another modification that improves brake performance is water cooling systems. For example, some cars have misting systems added to their brake ducts to keep them from overheating. These are unlikely to affect your premium.
A car can be lowered as long as this doesn’t affect the steering or headlight aim (there are strict specifications around headlight aim, as they have the potential to dazzle other drivers.)
Another issue faced with lowering a car is its ability to clear uneven road surfaces such as speed bumps. Over-lowering can also reduce the effectiveness of the way the car handles, putting the driver and passengers at risk. However, this modification is mainly cosmetic and unlikely to affect your premium.
Upgrading your car’s suspension may make a noticeable difference to its handling, but most cars have adequate suspension as standard. As such, you’re unlikely to see a change in the cost of your policy, unless your car is already heavily modified – in which case, you may save about 5%.
Bushings are small rubber or polyurethane suspension components that are used to isolate vibration, provide cushioning, and reduce friction between metal parts. Some drivers of cars with rubber bushings replace them with polyurethane bushings, as these typically last longer and do a better job of quelling vibrations and minimiing weight transfer. These won’t affect your insurance policy, but as with all modifications, you should still declare them.
When a car turns or swerves, the effect of the weight transfer onto one side can, over time, negatively impact handling. This is why some drivers install sway bars – also know as anti-roll or stabilizer bars – which help to reduce body roll by connecting the right and left wheels. Rather than the car leaning to one side, the sway bar helps to distribute the force equally – the bar goes down on the side it leans into, and up on the other side. It’s a little extra that can save you about 5% if you have a highly modified car.
Short shift kits are a popular mod that shorten the distance the lever needs to travel between gears. This means quicker shifts and a much sportier action – it can also make it more difficult to drive if you’re not used to it!
As this modification is associated with young drivers and racing, it can be a concern for some insurers. That said, it will only increase your premium about 5-10%, or maybe not at all if your car is already heavily modified.
Gear knobs can also be modified. Some drivers will choose to replace their existing one because it is worn, or they’d prefer something more ergonomic or aesthetically pleasing (e.g. leather, sparkly). Novelty options include skulls, gaming joysticks and film prop replicas. They may affect your ability to change gear, but they probably won’t change your insurance costs.
Track days became particularly popular in the 1990s after the introduction of speed cameras on Britain’s roads. As such people started to modify their cars for the track by adding roll cages and roll bars. These are frames built into the car to protect the driver and/or passenger in the event of an accident. It’s unlikely you’ll find an insurance company that will cover these under standard policies – you’ll need a specialist motorsport insurer like Adrian Flux.
Alloy wheels are much stronger yet lighter than steel ones of the same size, which improves car handling. This is because there will be less weight for the suspension to cope with and less resistance when you steer. The strength of alloy also means it will flex less around corners. Alloys are often ordered at the point of purchase for new cars, but they can also easily be an aftermarket modification.
If there’s a history of alloy wheel theft in the area where you live, your insurer may increase your premium. However, in an area with low-crime, getting alloys is unlikely to affect your premium.
Not all modifications are related to car performance. For example, spinning hub caps are purely aesthetic – spinning independently from the wheel to create an interesting effect. Other novelty hub caps can be patterned or light up. While these can be a theft risk, they are unlikely to affect your premium.
Replacing or reupholstering seats may be necessary depending on the age and wear of your car. Alternatively, you may just want to put in heated seats or even vintage-style tuck and roll. Whatever the reason, you should mention your modification to your insurer. You most likely won’t have additional costs if you already have a modified policy, but these modifications could increase a standard policy by 5-10%.
Sounds systems are a popular (and fairly cheap) mod. Most people will have seen – or more likely heard – a car with an aftermarket subwoofer. This is a speaker system designed to maximise low frequencies i.e. bass and sub-bass. Unless you opt for a high-value system, you won’t see a rise in your premium.
Some people also modify their dashboards. You may do this for functional reasons, such as adding a built-in satellite navigation system or car phone, or for aesthetics (wood or aesthetics.) These are unlikely to affect your premium.
There is a range of modifications to a car’s exterior that can impact your premium, from tinted windows to neon lights. While UK law states that there are no restrictions on tinting your rear windows and windscreen, the front windscreen and side-view windows do have restrictions. Legally, at least 75% of light must be allowed through the front windscreen and 70% of light through the front side windows. They won’t increase or decrease your cost of insurance cover.
Under-car neon lights remain a favoured modification. By law, you are not allowed to have the tubing visible and the light cannot be so bright that it will distract you or other road users (for example flashing lights are illegal.) Only white lights can be fitted to the head lights at the front and red lights to the back of the car. Washer jet LED lights are prohibited, especially coloured lights. Green lights may not be used at all.
In general, lights won’t increase your cost of insurance. But your insurer may take into account your claims history and theft risk, especially if you’re a younger driver, and require a supplement.
Many people are surprised to hear that custom paintjobs, decals and stickers are also classed as a modification by insurance companies. As such, some people get caught out when they try to make a claim and discover their insurance isn’t valid because they haven’t declared their bumper sticker collection or racing stripes.
Not all insurance companies cover stickers and custom paintjobs – it depends on claims they have had in the past. If the company has had to make large pay-outs for cars with these kinds of modifications, they may not be keen to cover them for other drivers. For insurers that do offer cover, they’re only likely to increase your premium by 5% at most.
Modifications that may reduce your insurance premium
While many modifications can increase your premium, there are mods that can reduce it because they improve driving safety and discourage theft. Using security devices, such as immobilisers, tracking devices and additional safety locks, are all ways to potentially reduce your premium. If your car is a 1995 model or earlier, adding an immobiliser can eliminate your theft risk and therefore reduce your premium. Installing a tracker to heavily modified car (£40,000 value or above) will also reduce the cost of cover for that vehicle.
Your premium is likely to be about 15% if you have bought a car and modified it yourself (or had a mechanic modify it to your specifications.) This is because the insurance company recognises that you have put time, energy and care into your car, and are less likely to treat it with disrespect or drive recklessly. In fact, some insurers will reduce your premium the more modifications you make!