Any modification to your car from its factory specification can affect your insurance. Some modifications increase premiums significantly.
What Counts as a Modification
| Type | Examples |
|---|---|
| Performance | Engine remap, turbo, exhaust, air filter |
| Suspension | Lowered springs, coilovers, air ride |
| Wheels | Alloy upgrade, different size |
| Bodywork | Spoiler, body kit, tinted windows |
| Interior | Aftermarket seats, steering wheel |
| Audio | Subwoofers, upgraded speakers |
| Styling | Decals, wraps, neon lights |
How Much Mods Increase Premium
| Modification | Typical Increase |
|---|---|
| Alloy wheels (upgrade) | 5-15% |
| Window tint | 5-10% |
| Body kit | 10-30% |
| Engine remap | 20-50% |
| Turbo/supercharger | 50-100%+ |
| Exhaust system | 10-25% |
| Lowered suspension | 10-25% |
Declaring Modifications
| What Happens If You Don’t Declare | Consequence |
|---|---|
| Your policy is void | No payout for ANY claim |
| You could be charged with fraud | Legal consequences |
| Third-party claims denied | You pay out of pocket |
Always declare every modification. If in doubt, ask your insurer.
Specialist vs Standard Insurers
| Insurer Type | Best For |
|---|---|
| Admiral | Mild modifications (wheels, tints) |
| Direct Line | Some modifications |
| Adrian Flux | All modifications |
| Brentacre | Heavy modifications |
| Greenlight | Young drivers with mods |
| Sky Insurance | Performance cars |
How to Reduce Premiums
| Tip | Saving |
|---|---|
| Add modifications one at a time | Spreading mods can cost less |
| Get a professional installation | Receipts prove quality work |
| Join a car club | Some offer insurance discounts |
| Limit modifications | The more you mod, the more you pay |
| Use a specialist broker | Better rates for modified cars |
| Increase security | Alarms, immobilisers, tracking |
Modified Car Insurance Tips
- Get quotes before modifying — Know the cost increase
- Keep original parts — Switching back at renewal can reduce costs
- Use a specialist — Standard insurers penalise mods heavily
- Be honest — Non-disclosure voids your policy
Bottom Line
Modified cars cost more to insure. Performance mods (remaps, turbos, exhausts) increase premiums most. Declare every modification — non-disclosure voids your policy. Use a specialist insurer for heavily modified cars. Get quotes before modding so there are no surprises.
What to remember
The most important rule with modified car insurance is simple: declare every modification. Even a change that seems minor — new alloy wheels, a window tint, or a different exhaust — must be told to your insurer. Non-disclosure is the fastest way to have a claim rejected entirely. Performance modifications like engine remaps, turbo kits, and superchargers increase premiums most dramatically, often by 50% or more. Cosmetic changes raise costs more modestly, typically in the 5-15% range. A specialist insurer will almost always offer better terms for modified vehicles than a standard provider, so it pays to shop around before accepting your current insurer’s renewal quote.
Errors that cost drivers money
The single most expensive mistake is failing to declare modifications. If you make a claim and the insurer discovers undisclosed work, your policy is void — meaning you pay for everything out of pocket, and any third-party claims fall on you personally. The second mistake is assuming standard insurers are the cheapest option. Many mainstream providers load premiums heavily for any modification, whereas specialist brokers are set up to assess modified vehicles fairly. A third common error is not keeping original parts when modifying. If you revert to factory specification before renewal, you can demonstrate the car has been returned to its standard state, which typically lowers the next premium. Finally, getting insurance quotes after the modification is already done removes your negotiating position. Know the cost impact before you commit.
Keep records of all modifications and professional installations. Receipts from a qualified garage prove the work was done to a proper standard, which matters both at resale and when demonstrating to your insurer that modifications meet safety requirements. If you later sell the car, a documented modification history typically supports a higher asking price because the buyer can verify exactly what was done and by whom. Managing the insurance cost of a modified car is ultimately about forward planning — knowing the premium impact before you mod, declaring every change honestly, and keeping your paperwork organised protects both your cover and your wallet.