Vehicle modification isn't exactly a hot new trend – we've been adding kit onto our cars for decades now, with some interesting results. But alterations, new parts and even bumper stickers are all changes that could affect how much you pay for your car insurance.
Data held by insurance companies mean that even innocent modifications such as upgrading your car's infotainment system could mean an increase in premiums.
Insurers' concerns aren't with the modification itself, but about what it says regarding the owner's driving style – not to mention the possibility of increased risk of vandalism or theft.
For example, adding a pricey sat nav to your car's dashboard could see premiums rise by as much as 10 per cent – as the car becomes more of a target for thieves.
Modifying your car for extra power or speed, meanwhile, could see your premiums double. Price comparison website Moneysupermarket says that just fitting an aftermarket exhaust pipe could add an extra £100 onto a £500-per-year premium, an increase of 20 per cent.
The prices are based on two factors. Insurers say that a faster car is more likely to crash, but they also fall back on data showing that drivers who modify their cars are more likely to make a claim.
Failing to disclose modifications to your insurer could lead to your policy being invalidated, meaning drivers must either keep their cars stock, or stomach potential extra costs from their insurer.
Some are so picky about it that in 2015, Age UK insurance threatened to invalidate a pensioner's policy after she fitted bumper stickers to her car, proclaiming 'Christ Must Be Saviour' and 'Christ for Me' to following traffic. A spokesperson for the AA said at the time: "Insurers are not bothered about you having a National Trust sticker in your back window - they are concerned about you making your car an advertising billboard or drawing attention to the vehicle, which could make it a target for people who disagree with those views."
It's not all bad news, though, as some vehicle modifications can actually reduce the price of your policy. Automatic emergency braking systems can reduce costs by up to 20 per cent, as they help mitigate or even prevent collisions altogether.
Fitting a dashcam may reduce your premiums, with the footage gathered cutting the time taken to process a claim by clearly showing who is at fault. And caravanners rejoice – fitting a towbar to your vehicle can cut insurance prices by up to a fifth.