Owning a modified car may be cool to you and me, but unfortunately a lot of car insurance companies don't seem to agree. Many providers hike their premiums based on the modifications you have made, which is why we've put together this guide to help you keep your car insurance costs in check.

Why do modified car drivers pay more for insurance?

Car insurers take a number of factors into account when they assess premiums including your driving history; your address; your personal circumstances; your annual mileage; and yes, the car you drive.

The repair costs, security features, performance capabilities and value of a car are all taken into account when car insurance premiums are analysed. In the case of modifications they typically add to a car's value and can cost more to repair/replace - therefore they often push insurance premiums up.

To illustrate the point we compared the car insurance quotes available to a 28-year-old male Ford Focus ZETEC driver from Cheshire. His cheapest quote without modifying the car at all was just £503.90 a year. However, making a number of individual modifications to his car saw his quotes rise steeply:

- Cheapest quote with non-standard alloy wheels: £668.50.
- Cheapest quote with up-rated brakes: £703.15.
- Cheapest quote with flared wings: £720.73.
- Cheapest quote with exhaust system changes: £738.80.
- Cheapest quote with non-standard paintwork: £813.47.

Remember these are the quotes for these modifications individually. If the same driver added all of these modifications to his car, his cheapest car insurance quote would be £974.26 a year.

So how can modified car drivers get an affordable deal?

For drivers of modified cars it becomes increasingly important to evaluate as much of the marketplace as possible before settling on the right car insurance deal for them.

Thankfully in recent years a number of specialist car insurance companies have emerged which claim to offer better deals for modified car drivers because they recognise that these motorists are more likely to take care of their vehicles. As such they tailor their policies with a number of specialist features including:

- Advanced driving discounts: There may be money off if you complete an advanced driving course such as a Pass Plus or IAM course.

- Agreed valuations: The value of modified cars can be difficult to determine and if your vehicle were written-off or stolen it could be undervalued by a standard insurer. However, with an agreed valuation you'll know from the outset what your car is worth so you can be confident you won't be short-changed.

- Limited mileage discounts: As many modified car drivers only use their vehicles on special occasions they may be able to save money by agreeing to a mileage cap.

- Owners' club discounts: If you are a member of an owners' or manufacturer's club then you may be able to save money on your car insurance.

- Rally/Track cover: Most insurers would not cover your vehicle if you planned to enter it into a rally or track race. However, some modified car insurers will.

Certainly these added incentives are well worth considering. However, you should still shop around for car insurance using a comparison website before you buy. Most of the leading comparison websites will compare rates from standard car insurers and some specialists too meaning you can get an overview of the deals available.

Other tips to drive premiums down

If you're a modified car driver you should take all the steps you can to drive down your premiums to make up for the fact that your car is likely to be a touch more expensive to insure. Here are some tips:

- Annual payments: Insurers like to know their money is secure and so it's cheaper to pay upfront rather than paying monthly when interest charges are often added.

- Be secure: Car alarms, immobilisers and tracking devices are the sort of modifications that even insurers love. Implement approved devices and you'll limit the risk of theft and should earn a substantial discount.

- Drive safely: Most insurers offer no-claims discounts if you can steer clear of accidents - they could be worth as much as 60 per cent off your premiums after four or more years.

- Increase your excess: Think about how much you can comfortably afford to pay on your voluntary excess in case an accident occurs as increasing the excess level should lower your premiums.

- Named drivers: Limit the number of named drivers on your policy as motorists with poor driving records are likely to force your premiums up.

- Park safely: Modified cars can attract the attention of thieves and vandals so keep your vehicle in a locked garage overnight.