The Vehicle Identification Number (V.I.N)

Modern VINs consist of 17 characters, divided into three sections:

  • WMI (World Manufacturer Identifier, 1–3)
  • VDS (Vehicle Descriptor Section, 4–9)
  • VIS (Vehicle Identifier Section, 10–17)

How chassis numbers evolved into today’s VINs, why the change happened, how the VIN is structured, and where the main exemptions and special cases exist:

Quick chronology (UK & Europe)

  • 1903–1904 – registration plates introduced. The Motor Car Act 1903 required vehicles to be registered and display number plates from 1 January 1904; early local registers often recorded make/owner and sometimes engine/chassis numbers, but there was no national format. (Wyas Catablogue, Wiltshire and Swindon History Centre)
  • Pre-1970s – manufacturer serials only. British makers stamped their own chassis/frame and engine numbers (often both). Engine numbers were widely used as the administrative identifier on older vehicles, which later proved problematic as engines were swapped. Examples: Ford Model A practice; MG T-Types; general vintage practice. (mafcgb.org.uk, vintagecarparts.co.uk, MG Car Club)
  • 1977–1983 – international standardisation. ISO issued the first VIN standards: ISO 3779 (content/structure) and ISO 3780 (WMI—World Manufacturer Identifier), plus ISO 4030 (location/attachment). British Standards adopted aligned documents (BS AU 175 series) in 1979. (Iteh, Scribd)
  • 1980s – UK legal requirement to mark a VIN. The UK’s Road Vehicles (Construction and Use) Regulations 1986, Regulation 67 require a vehicle identification number to be marked on the chassis/frame and on a plate for vehicles first used on/after 1 April 1980 (as consolidated). (Legislation.gov.uk)
  • EU type-approval era. Directive 76/114/EEC (statutory plates and inscriptions) was carried forward and modernised by Regulation (EU) No 19/2011, which requires a VIN on each vehicle and 30-year traceability; it recast the older directive in the EU type-approval framework. The UK followed this regime while in the EU. (Eur-Lex)
  • Today (GB). Post-Brexit, GB type-approval is implemented domestically (e.g., Road Vehicles (Approval) Regulations 2020), but VIN content/marking expectations remain aligned to ISO/EU practice. DVLA guidance still requires every UK-registered vehicle to have a unique, stamped-in VIN. (GOV.UK)

Why the VIN was introduced

  • Unify identification across makes/markets to fight fraud and support recalls, safety campaigns and traceability—hence the world-wide ISO 3779/3780 standards, later embedded in EU/UK type-approval rules. (ISO, Eur-Lex)
  • Replace disparate chassis/engine numbers that weren’t unique nationwide and frequently changed with component swaps. (mafcgb.org.uk)
  • Regulatory control. EU rules require the VIN to be unique, marked on the vehicle when it leaves the production line, and traceable for 30 years. (Eur-Lex)

How a modern VIN breaks down (UK/EU practice)

Modern VINs are 17 characters (digits and capital letters, excluding I, O, Q). They’re split into three sections: (Iteh, GOV.UK)

  1. WMI (World Manufacturer Identifier) – positions 1–3 identify the manufacturer and (broadly) region/country. UK WMIs commonly start with S (e.g., SAJ = Jaguar, SAL = Land Rover). WMIs are assigned under ISO 3780; SAE acts as the global Registration Authority for WMIs. (sae-itc.com, Wikipedia)
  2. VDS (Vehicle Descriptor Section) – positions 4–9 describe vehicle characteristics (body, restraint, engine…); content is manufacturer-defined within the standard. The 9th position is a check digit in North America, but it’s not mandatory in Europe. (Wikipedia)
  3. VIS (Vehicle Identifier Section) – positions 10–17 uniquely identify the individual vehicle (often including model year/plant in North America; EU does not require a model-year code). (Wikipedia)

Marking/location. EU/UK rules require the VIN to be stamped or hammered into the chassis/frame (or equivalent) and also shown on the manufacturer’s statutory plate; IVA manuals and EU Reg 19/2011 detail the marking methods (single line, characters allowed, visibility, etc.). (Legislation.gov.uk, GOV.UK)

UK legal position & administration

  • C&U Regs (Reg. 67) – VIN must be marked on vehicles first used since 1 April 1980. (Legislation.gov.uk)
  • Type-approval – Under EU Reg 19/2011 (followed by the UK until Brexit), manufacturers must mark a VIN, ensure uniqueness, and maintain traceability for 30 years. (Eur-Lex)
  • DVLA practice – “All vehicles registered in the UK must have a unique, stamped-in VIN.” If a vehicle is rebuilt/modified such that its identity is unclear (e.g., new/altered chassis or monocoque), DVLA can allocate a new DVLA VIN and the vehicle may receive a ‘Q’ registration after an IVA/MSVA inspection. DVLA explains these cases in current guidance and its 2024–25 call-for-evidence documentation. (GOV.UK)

Exemptions, variations & cases that don’t use the full 17-char ISO format

A) Pre-standard vehicles (pre-1981)

  • Many UK classics predate the modern VIN and have shorter chassis/frame numbers (or relied on engine numbers). DVLA and heritage bodies recognise this; such vehicles are not retro-required to adopt a 17-char VIN. Stakeholders (e.g., HCVA) stress that pre-1981 vehicles shouldn’t be forced to meet post-1981 VIN uniqueness rules. (Historic & Classic Vehicles Alliance)

B) Rebuilt/kit/‘radically altered’ vehicles

  • Where originality of the chassis/monocoque cannot be substantiated—or a non-original frame is used—DVLA allocates a DVLA VIN and usually issues a Q-plate. Public-facing guidance and sector commentary describe the widely seen SABTVRO… DVLA-assigned VIN prefix in such cases. (GOV.UK, Historic & Classic Vehicles Alliance, Green Flag)

C) Some imports (esp. older or certain Japanese-market vehicles)

  • Consumer-facing UK guidance notes that imports from outside Europe may present shorter VINs (or non-standard layouts) depending on age/market. These typically rely on the original chassis/frame number when registered.

D) Prototypes and special-use vehicles

  • Prototype vehicles used on public roads can receive limited exemptions from various construction rules under the UK’s “special types” order, though identification requirements still apply when registering/approving the vehicle. (GOV.UK)

E) Low-volume manufacturers (EU rule: ≤500 vehicles/year)

  • ISO/EU allow a special low-volume format: the 3rd VIN character is “9”, and extra maker identification moves into VIS positions 12–14, assigned by the national body. Many boutique UK marques historically used SA9… VINs under this rule. (Iteh, Wikipedia)

The Low-Volume Rule

    ISO 3780 and EU/UK type-approval allow a special arrangement for manufacturers producing ≤500 vehicles per year. In these cases, the 3rd character of the VIN = “9” (e.g. SA9… if UK-based).

    Because the WMI (World Manufacturer Identifier) cannot cover so many small firms, the national authority (in the UK: DVLA) assigns the detail codes in the VIS (positions 12–14) to identify the manufacturer.

    Examples of UK/EU Low-Volume VINs

    • Morgan Motor Company (pre-2010s models). VINs often start SA9… (e.g. SA9MGBE1…), before Morgan’s volume and approvals aligned with standard Jaguar Land Rover-style WMIs.
    • Lotus (special editions/early models). Some low-run cars (esp. in the 1980s–90s) carried SA9 prefixes when UK approval was handled as small-series.
    • TVR Engineering. TVR sports cars often carried SA9TVR… VINs.
    • Noble Automotive. Supercars (Noble M10, M12, M400) have VINs beginning SA9N….
    • Caterham Cars. Some Caterham 7s are registered with SA9… VINs.

    Other UK boutique marques (examples documented):

    • Westfield Sportscars (kit/production runs)
    • Ultima Sports
    • Marcos Engineering (revival models)
    • Ginetta (certain series, when under 500/year)
    • Bristol Cars (hand-built saloons, 1980s–2000s)

    What “SA9” means

      S = United Kingdom (region code)
      A = assigned by UK authority (VCA/DVLA)
      9 = low-volume manufacturer flag

      Positions 12–14 in the VIN identify the actual marque (Morgan, Noble, TVR, etc.), assigned by the VCA.

      Today

        This system still exists in UNECE/EU regs and is retained by GB type-approval. Many small marques (Morgan, Caterham, Noble, Ariel, BAC Mono) are covered. Once a maker goes above 500/year, they must apply for a full, standard WMI (e.g. Morgan now often uses SAJ/SAK allocations).

        Practical decoding & marking specifics

        • Characters allowed: the letters I, O, Q are not permitted in a VIN. (UK IVA inspection manual note.) (GOV.UK)
        • VIN must be physically marked on the chassis/frame (or equivalent) and appear on the statutory plate; EU rules prescribe stamping/hammering and single-line presentation. (Legislation.gov.uk)
        • Manufacturer traceability: EU requires manufacturer-level VIN traceability for 30 years. (Eur-Lex)

        Sources & further reading

        • DVLA (gov.uk): “Vehicle identification number (VIN)” – policy that every UK-registered vehicle must have a unique, stamped-in VIN; notes on loss during rebuilds. (GOV.UK)
        • UK law: Road Vehicles (Construction and Use) Regulations 1986, Regulation 67 (VIN marking). (Legislation.gov.uk)
        • EU/Type-approval: Regulation (EU) No 19/2011 (statutory plate & VIN)—VIN must be marked; uniqueness; 30-year traceability; marking methods. (Eur-Lex, Legislation.gov.uk)
        • ISO standards: ISO 3779 (content/structure), ISO 3780 (WMI), ISO 4030 (location/attachment). (Iteh, ISO, Scribd)
        • British Standards (historical): BS AU 175 (1979) series mirroring VIN content, WMI and location—evidence list. (content-lists.sl.nsw.gov.au)
        • IVA inspection manual (UK): VIN character restrictions and marking practice (example: N2/N3 manual excerpt). (GOV.UK)
        • Historic/classic policy (DVLA/HCVA): DVLA call-for-evidence & sector responses—new DVLA VIN allocation and Q-plates; stance on pre-1981 identifiers. (GOV.UK, Historic & Classic Vehicles Alliance)
        • Background/history: Early UK registration history; vintage practice using engine/chassis numbers. (Wiltshire and Swindon History Centre, mafcgb.org.uk, vintagecarparts.co.uk)
        • Check-digit & EU vs US differences: overview showing check digit mandatory in North America but not Europe. (Wikipedia)