How Does Modified Car Insurance Work?
In a Nutshell: Modified cars require special insurance because standard policies typically don't cover aftermarket parts, engine modifications, or custom paint. If you modify your car without telling your insurer, most will deny claims for damage to those modified parts. A "stated value" or "modified car" policy adds coverage for custom parts, typically costing 10–30% more than standard coverage.
Modifications That Affect Insurance
| Modification Type | Impact on Premium | Notes |
|---|---|---|
| Engine tuning/ECU flash | +20–40% | Performance increases = more risk |
| Turbo/supercharger | +30–50% | Significant power increase |
| Suspension lowering | +10–25% | Handling changes, scrape risk |
| Custom wheels | +10–20% | Replacement cost, theft target |
| Body kit | +15–30% | Expensive to replace |
| Custom paint/wrap | +10–20% | Higher repair costs |
| Audio/video system | +5–15% | Theft risk, expensive components |
| Performance exhaust | +10–20% | Noise, performance signal |
| Window tint | +0–10% | Minimal impact alone |
Any modification that increases vehicle value or performance will increase premium. Some modifications (disable safety features, remove airbags) may result in denial of coverage.
Standard vs. Modified Policy
| Coverage Area | Standard Policy | Modified Policy |
|---|---|---|
| Aftermarket parts | Up to $1,000–$3,000 | Declared full value of parts |
| Engine modifications | Excluded | Covered if declared |
| Custom paint | Excluded | Specific coverage |
| Wheels/tires | Replacement value only | Stated value for custom wheels |
| Audio system | $1,000–$2,000 max | Declared value coverage |
| Total loss payout | ACV (no mods valued) | Stated value with modifications |
| Premium impact | Baseline | +10–50% depending on mods |
Insurers That Cover Modified Cars
| Insurer | Best For | Typical Premium Increase | Notes |
|---|---|---|---|
| Progressive | All mod types | +15–30% | Custom Parts and Equipment coverage |
| Hagerty | Highly customized | +10–20% | Best for show cars |
| Grundy | Restomods, rods | +10–25% | Agreed value on modded cars |
| State Farm | Moderate mods | +10–20% | Agent-dependent |
| Geico | Minor mods | +5–15% | Limited aftermarket coverage |
| Allstate | Audio/video | +10–25% | Good for sound system coverage |
If your car is heavily modified (engine swap, turbo, full custom), go with a specialty insurer like Hagerty or Grundy. Standard insurers may not adequately cover major modifications.
How to Declare Modifications
| Step | Action |
|---|---|
| 1 | Document all modifications with photos and receipts |
| 2 | Calculate total value of aftermarket parts |
| 3 | Contact your insurer and declare all modifications |
| 4 | Request Custom Parts and Equipment (CPE) coverage |
| 5 | Get a stated value or agreed value policy if needed |
| 6 | Update coverage each time you add new modifications |
| 7 | Keep all receipts and documentation in a safe place |
When declaring mods, be specific. "Cold air intake" is different from "full turbo kit" — both change the premium.
Modifications That May Void Standard Coverage
| Modification | Risk |
|---|---|
| Disabling safety systems (airbags, ABS) | Insurer may deny injury claims |
| Major engine swap (e.g., V8 into a 4-cylinder car) | Must be declared or denied |
| Removed catalytic converter (fed law) | Coverage may be voided |
| Roll cage in street car | May limit passenger coverage |
| Nitrous oxide system | Often excluded from coverage |
| Track-only modifications (racing slicks, harnesses) | Street coverage may not apply |
Tips for Modified Car Owners
- Tell your insurer BEFORE installing mods — Not after
- Keep ALL receipts — You need proof of value for claims
- Take detailed photos — Document the car from all angles
- Get a stated value policy — Protects the total value including mods
- Consider a specialty insurer — Hagerty, Grundy for heavily modified cars
- Review coverage at renewal — Add new mods to the policy
- Separate audio coverage — High-end audio systems may need a separate rider
Key Takeaways
- Standard policies cover aftermarket parts only up to $1,000–$3,000 in most cases
- Modified car policies cost 10–50% more but cover the full value of modifications
- Always declare mods to your insurer — failure to do so can void claims
- Heavy modifications need specialty insurers (Hagerty, Grundy)
- Document everything: receipts, photos, appraisals
- Update your coverage every time you add new modifications
- Some modifications (safety system removal) may result in claim denial
Last updated: July 2026
Disclaimer: This article provides general information about modified car insurance. Coverage availability and policy terms vary by insurer and state. Always declare modifications to your insurer and consult with a licensed agent for advice specific to your situation.