What is a VIN or Chassis Number?

What Is a Vehicle Identification Number (VIN)?

A Vehicle Identification Number (VIN), also known as a Chassis Number is a unique 17-character code assigned to every car, van, and light commercial vehicle when it’s manufactured. It acts as the vehicle’s fingerprint, containing key details about its make, model, and production history.

Your VIN is displayed on your vehicle and recorded on official documents. If you’re unsure where to locate it, see our guide on where to find your VIN or chassis number.

Where Is a VIN Recorded?

Each VIN is permanently linked to a specific vehicle and recorded across a range of official systems and databases, including:

• Accident and insurance reports
• Service and repair records
• Vehicle registration and ownership databases

These records allow the VIN to be used as a consistent reference for identifying a vehicle and linking its history across trusted data sources, including those used in a MotorCheck Vehicle History Report.

VIN Format and Key Details

• Vehicles made after 1981 use a 17-character VIN.
• Older vehicles (before 1981) may have shorter VINs.
• The letters I and O are never used — they’re replaced with numbers 1 and 0 to avoid confusion.
• Most vehicles built since 1969 display the VIN on the driver’s side dashboard.

How a VIN Number Is Structured

In the UK, VIN standards follow international regulations, with manufacturer identifiers issued by national standards bodies.

A VIN is divided into three main sections, each revealing different information about the vehicle.

Section 1: World Manufacturer Identifier (WMI)

The first three characters of the VIN form the WMI, which identifies the vehicle manufacturer.
Each manufacturer is assigned a unique code to ensure every VIN remains globally unique.

In Ireland, the NSAI (National Standards Authority of Ireland) issues WMI codes under international standard ISO 3780.
If a manufacturer produces fewer than 500 vehicles per year, the third WMI character is “9,” and characters 12–14 of the VIN are assigned by the NSAI.

Section 2: Vehicle Descriptor Section (VDS)

The next six characters describe the vehicle’s general attributes such as body style, engine type, and model.

Manufacturers decide how to code this section, and unused spaces may be filled with random alphanumeric characters.

Section 3: Vehicle Identifier Section (VIS)

The final eight characters provide information unique to that specific vehicle.
Typically:

• The first character indicates the model year.
• The second character indicates the manufacturing plant.
• The last four digits are a serial number that differentiates each vehicle.

The Purpose of a VIN Number

The VIN plays a vital role across many areas of vehicle ownership, safety, and administration.

1. Vehicle Identification

Each VIN is unique, no two vehicles share the same number. This ensures clear identification for registration, legal, and resale purposes.

2. Theft Prevention and Recovery

If a vehicle is stolen, authorities use the VIN to help track and recover it.
Even if thieves remove visible VINs, hidden ones can still confirm the car’s identity.

3. Recalls and Safety Notices

Manufacturers use VINs to notify owners of recalls or service actions.
If a specific production batch has a defect, the VIN helps identify the affected vehicles.

4. Vehicle History and Write-Off Records

The VIN allows access to a car’s entire history, including ownership, accidents, write-offs, and repairs.
It’s the key reference in a MotorCheck Vehicle History Report.

5. Insurance and Valuation

Insurance providers use VINs to verify the car’s make, model, and year helping calculate accurate premiums and validate claims.

6. Production and Registration

VINs help government agencies and manufacturers manage registration, taxation, and compliance records.

7. Decoding Vehicle Specifications

The VIN encodes details such as engine size, transmission, model year, and manufacturing location.

8. Authenticity and Value

For classic and vintage cars, the VIN confirms authenticity and can significantly affect a vehicle’s value and collectability.

Why VINs Are Important

Your VIN is more than just a number, it’s your vehicle’s unique fingerprint.
It ensures traceability, safety, and transparency across the automotive industry from manufacturing and registration to resale and recall management.

To access a vehicle history report, simply enter the registration number (VRM) on the MotorCheck website, which retrieves records linked to the vehicle’s VIN.

Get a MotorCheck Report Today

Understanding your VIN or chassis number is key to knowing a vehicle’s true identity and history. Because the VIN is permanently linked to a vehicle throughout its lifetime, it’s the most reliable way to verify details such as ownership records, accident history, and write-off status.

A MotorCheck Vehicle History Report brings together verified records linked to a vehicle’s VIN. To access a report, simply enter the vehicle registration number on the MotorCheck website and view the vehicle’s background in seconds.