This instrument sets uniform technical prescriptions for approval of vehicle types with regard to speedometer equipment and its installation for vehicles of categories L, M and N (Regulation No. 39, Scope). Mechanically, it creates a type-approval pathway: manufacturers (or their accredited representatives) submit a type description and an unladen representative vehicle to a technical service for tests (paras 3.1-3.3). If the technical and administrative requirements are met, an approval number is issued and an international approval mark must be affixed to each vehicle of the approved type (paras 4.1-4.4, 4.6-4.7, Annex 2). The Regulation prescribes the physical design and legibility of speedometer displays, graduations, and labelling in metric and, where required, imperial units (para 5.1 and subparagraphs). It prescribes the accuracy standard for the approval test (para 5.3), the test conditions (para 5.2), and a separate conformity-of-production test regime including the specific production test in Annex 3 (paras 7.1-7.4, Annex 3). It requires competent authorities to verify production conformity at normal intervals of once every two years (para 7.4) and gives the authority power to withdraw approval where conformity procedures are not met (para 8.1-8.2).

The text frames uniformity and reciprocal recognition as the operational objective: approvals under this Regulation are to be communicated among Contracting Parties, and Parties must list their technical services and administrative departments with the United Nations secretariat (paras 4.3, 9). The instrument therefore changes the mechanics of market entry for vehicle types by conditioning lawful representation of type conformity on documented approval, marked identification and ongoing conformity control.

Costs and decision points are concentrated on manufacturers, technical services and the administrative department that issues approval. Manufacturers must fund testing, supply vehicles and documentation in triplicate (para 3.2), meet requirements of the test procedures (para 5.2 and Annex 3) and maintain conformity systems in line with Agreement Appendix 2 as adopted by this Regulation (para 7.1). Administrative departments decide whether a modification requires further testing (para 6.1). The only express formal sanction is withdrawal of type approval (para 8.1); the Regulation does not prescribe monetary fines or criminal penalties in its text. The approval mark and approval-number mechanics create an information mechanism for regulators and market actors, and the Regulation places procedural obligations on Parties to communicate approvals and withdrawals (paras 4.3, 8.2).

The Regulation defines a discrete set of concepts that structure obligations and tests. "Approval of a vehicle" is defined narrowly as approval of a vehicle type with regard to the speedometer equipment and its installation (para 2.1). A "type of vehicle in respect of its speedometer" is a technical construct that groups vehicles that do not display essential differences in items listed at para 2.2, including tyre size designation (para 2.2.1), the overall transmission ratio to the speedometer (para 2.2.2), and speedometer characteristics (para 2.2.3 and subparagraphs). This focuses regulatory granularity on any attributes that alter the relationship between vehicle motion and the speedometer reading, rather than on unrelated vehicle features.

Tyre-related definitions matter for testing. "Tyres normally fitted" means the tyres provided by the manufacturer on that vehicle type and explicitly excludes snow tyres (para 2.3). "Normal running pressure" is defined as the cold inflation pressure specified by the manufacturer increased by 0.2 bar (para 2.4), and the test protocol requires tyres at that pressure during speedometer accuracy measurement (para 5.2.4). "Unladen vehicle" is precisely described, including a 75 kg driver and the inclusion of standard equipment like tools and a spare wheel if provided (para 2.6); this affects inertial and load conditions for tests.

Speedometer-specific terms are set out: "speedometer" means the part indicating speed to the driver (para 2.5) and the "tolerances of the speedometer's measuring mechanism" and "technical constant" are defined in para 2.5.1-2.5.2 as the instrument accuracy limits and the relationship between input pulses and displayed speed. These definitions underpin the measurable parameters required during approval and production checks.

Test regimes are separated into two regimes: initial type approval testing (paras 3-5) and conformity of production (paras 7 and Annex 3). Approval testing requires an accuracy relationship at specified test speeds (para 5.3), with the general rule that indicated speed must not be less than true speed and must satisfy 0 ≤ (V1 − V2) ≤ 0.1 V2 + 4 km/h at the approval stage (para 5.3). Conformity of production tests set different tolerance bands depending on vehicle category (Annex 3). The Regulation also specifies test infrastructures such as measurement instrument accuracy ±0.5 per cent (para 5.2.6), test track surface conditions (para 5.2.6.1), and a minimum roller diameter when a dynamometer is used (para 5.2.6.2). Administrative mechanics include assignment and format of approval numbers, and the requirement for approval communications to conform to Annex 1 (paras 4.2-4.3).

Directly affected actors are vehicle manufacturers, their accredited representatives, technical services that perform approval tests, and administrative departments in Contracting Parties that grant type approvals. The Regulation expressly provides that applications are to be made by the vehicle manufacturer or their accredited representative (para 3.1). Manufacturers must prepare the descriptive documentation in triplicate (para 3.2.1) and present an unladen representative vehicle for testing (para 3.3). Manufacturers therefore carry the primary compliance costs: preparing documentation, providing test vehicles, ensuring equipment and installations meet the display, graduation and accuracy requirements (para 5.1 and para 5.3), and implementing conformity of production systems that meet Agreement Appendix 2 (para 7.1).

Technical services bear the operational burden of conducting tests and generating reports. The Regulation contemplates a network of technical services responsible for approval tests; Parties must provide the names and addresses of these services to the UN secretariat (para 9). A technical service must execute the specified test procedures, including the accuracy tests, temperature control at 23 ± 5 °C (para 5.2.3), tyre pressure and tyre selection, and the measurement instrumentation accuracy (para 5.2.6). Administrative departments grant approvals, assign approval numbers, decide upon whether modifications require further testing (para 6.1), verify conformity of production procedures at production facilities (para 7.4), and may withdraw approvals where conformity fails (para 8.1).

Regulatory counterparts and market intermediaries are also implicated. Contracting Parties applying the Regulation must communicate approvals, refusals, extensions and withdrawals to each other using the Annex 1 form (para 4.3, para 6.2, para 8.2). This creates informational obligations between national regulators and supports reciprocal recognition mechanisms. Vehicle buyers and registration authorities are affected indirectly because the approval mark and the approval number are the visible signs that a vehicle type meets the Regulation’s requirements (paras 4.4-4.7, Annex 2). Inspections and enforcement at point-of-sale, importation or registration will typically rely on these markings and the underpinning approvals.

Lastly, suppliers of tyres and aftermarket speedometer equipment are affected because the type notion includes tyre size designation and the overall transmission ratio to the speedometer (para 2.2.1-2.2.2). Any change in those elements may trigger a modification communication to the approving department and potentially further testing (para 6.1).

Duties are primarily borne by manufacturers and by the administrative and technical authorities specified in the Regulation. Manufacturers must:

• Submit an application for type approval in triplicate accompanied by particulars described at para 3.2, including description of items listed at para 2.2-2.5.
• Provide an unladen representative vehicle for testing (para 3.3).
• Ensure the speedometer display is within the driver's direct field of view, legible day and night, and shows a sufficiently wide range to include the manufacturer's stated maximum speed; follow graduation and labelling rules for specific vehicle categories and for vehicles manufactured for sale in countries using imperial units (para 5.1 and subparagraphs).
• Ensure speedometer accuracy at approval testing meets 0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h for the approval test (para 5.3) and that production vehicles meet the conformity limits set in Annex 3 for their category.
• Maintain conformity of production procedures that comply with Agreement Appendix 2 (para 7.1) and undertake the specified checks, including Annex 3 tests for each vehicle type in production (para 7.3).
• Affix the approval mark close to or on the manufacturer's vehicle data plate, ensuring legibility and indelibility (paras 4.4-4.7, Annex 2).

Administrative departments have duties to:

• Verify the existence of satisfactory arrangements for effective control of production conformity before granting type approval (para 3.4).
• Assign approval numbers in the specified manner and communicate approval outcomes to Contracting Parties using Annex 1 (paras 4.2-4.3).
• Verify, at normal intervals once every two years, production conformity control methods at manufacturing facilities (para 7.4).
• Take steps to restore conformity if unsatisfactory results are found (para 7.5).
• Withdraw approvals where production conformity procedures are not met or vehicles have failed checks (para 8.1) and notify other Contracting Parties of withdrawals (para 8.2).
• Accept communications of modifications and decide whether further tests are required (para 6.1-6.2).

Technical services have the right to receive test specimens and associated documentation for the purposes of approval testing (paras 3.2-3.3) and to report test results to the administrative department (para 6.1.2 contemplates requiring further test reports).

Contracting Parties have an administrative duty to publish the names and addresses of their technical services and administrative departments with the UN secretariat so other Parties know where to send approval communications (para 9). This creates a mutual-rights structure: approval granted in one Party becomes communicable and recognisable among the Parties applying the Regulation, subject to the mechanics of international agreements noted in paras 4.3 and 9.

The Regulation specifies administrative enforcement mechanisms, but does not create monetary fines or criminal sanctions within its text. The principal sanction available is withdrawal of the type approval if a manufacturer fails to maintain the conformity of production procedures required by para 7.1 or if vehicles fail the checks prescribed in para 7 (para 8.1). Paragraph 8.2 requires that if a Party withdraws an approval it must notify other Contracting Parties applying the Regulation by means of the Annex 1 communication form; this ensures that withdrawal has cross-border informational effect among Parties.

Enforcement is operationalised through periodic verification and testing. Competent authorities have an express power and duty to verify production conformity control methods in each production facility, with a normal verification frequency of once every two years (para 7.4). Where verifications and checks yield unsatisfactory results, the competent authority must ensure necessary steps are taken to restore conformity as rapidly as possible (para 7.5). Administrative departments may also demand further test reports from the technical service when modifications are notified (para 6.1.2), which functions as a conditional enforcement trigger for ensuring modifications do not undermine compliance.

Technical requirements are enforced by measurable parameters. Speedometer accuracy tests must be conducted under specified test conditions,temperature at the speedometer 23 ± 5 °C (para 5.2.3), tyres at normal running pressure (para 5.2.4), and instrumentation accurate to ± 0.5 per cent (para 5.2.6). The Regulation declares the permissible relationship between indicated speed and true speed at the approval stage (para 5.3) and sets alternative production conformity bands in Annex 3. Failure to meet those measurable tolerances during approval or production checks triggers the administrative enforcement measures noted above.

There is a procedural dimension to enforcement: approvals are visible through the approval mark and number affixed to the vehicle (paras 4.4-4.7, Annex 2). The mark is required to be clearly legible and indelible (para 4.6) and is to be placed close to or on the manufacturer's vehicle data plate (para 4.7), making it a compliance signal for registration and inspection authorities.

The Regulation relies on Contracting Parties' domestic implementation for punishments beyond withdrawal, because it only prescribes administrative withdrawal as the sanction. The instrument requires Parties to communicate names and addresses of responsible technical services and administrative departments to the UN secretariat (para 9), enabling inter-state communications on enforcement outcomes. The text does not prescribe international dispute-resolution mechanisms or appeals procedures for withdrawn approvals; those mechanisms must be found in the broader Agreement or national law, which this Regulation references but does not reproduce (see para 7.1 referencing the Agreement, Appendix 2).

The Regulation is an ECE instrument operating within the framework of the Agreement concerning uniform technical prescriptions and reciprocal recognition of approvals. It expressly requires conformity of production procedures "comply with those set out in the Agreement, Appendix 2 (E/ECE/324-E/ECE/TRANS/505/Rev.2)" (para 7.1). That reference incorporates a separate procedural framework for conformity of production into the Regulation’s obligations; implementation therefore depends on Parties’ adherence to the Agreement’s Appendix 2 provisions.

Paragraph 4.5 anticipates stacked type approvals: where a vehicle conforms to types approved under other Regulations annexed to the Agreement in the same approving country, the symbol prescribed in para 4.4.1 need not be repeated and additional numbers and symbols are to be placed to the right in vertical columns. This creates explicit labelling interoperability with other ECE Regulations (para 4.5). The approval numbering rule in para 4.2 links approval numbers to the series of amendments of this Regulation, which interacts with amendment and transitional rules under the Agreement.

The Regulation requires Contracting Parties to communicate approvals, extensions, refusals and withdrawals using the Annex 1 form (paras 4.3, 6.2, 8.2). That communication obligation interfaces with national administrative law processes: Parties must decide how and under what domestic legal procedures they will issue approvals, handle amendments, and notify international partners. The Regulation itself does not set out domestic enforcement penalties beyond administrative withdrawal, so Parties will rely on their own national laws to implement sanctions, appeals and compliance processes that flow from this instrument.

Operational interactions with product standards and market regulation are implicit. The Regulation’s definitions tie approval to tyre sizes and transmission ratios (para 2.2), which means that changes in national tyre safety regimes, import restrictions on tyres, or rules on aftermarket speedometer alteration will affect whether a vehicle remains of the approved type. The requirement to affix an approval mark close to or on the manufacturer's vehicle data plate (para 4.7) interacts with vehicle registration and identification laws at the national level; registration authorities generally use such plates and marks to determine legal compliance at the point of registration or roadworthiness checks.

Finally, the Regulation does not displace other national obligations that may regulate speed-limiting devices, odometer fraud, consumer protection, roadworthiness inspections, or criminal prohibitions on fraud. It creates a harmonised technical baseline for type approval and for mutual information exchange among Contracting Parties, but the Regulation’s enforcement relies on Parties’ national procedures and the Agreement’s broader conformity mechanisms referenced at para 7.1.

The text indicates it is Revision 2 of Regulation No. 39 and states that Revision 2 includes amendments which entered into force on 16 October 1995; it also records an Addendum 38 and refers to Supplement 5 to the original version of the Regulation with a date of entry into force of 7 December 2002 in the document header. These elements are presented on the front matter of the text, which shows a layering of revisions: "Revision 2, including the amendments which entered into force on 16 October 1995" and a note about "Supplement 5 to the original version of the Regulation - Date of entry into force: 7 December 2002." The document therefore contains at least two historical markers: the 1995 series of amendments incorporated into Revision 2 and the Supplement 5 entry into force in 2002. The header also indicates the text is Addendum 38, Regulation No. 39, and refers to "Revision 1" text elements; the formatting suggests successive consolidations but does not provide a detailed amendment chronology within the body.

The approval-number rule in para 4.2 embeds an operational amendment-tracking mechanism: the first two digits of each approval number are to be the highest number of the series of amendments incorporated in the Regulation at the time of issue. That rule gives concrete effect to amendment status for any given approval number and enables regulators and market actors to identify the amendment series applicable to a particular approval. Annex 2’s illustrative approval marks include explanatory notes that the approval numbers indicate approvals granted "in accordance with the requirements of Regulation No. 39 in its original form" for the example approvals shown, which is consistent with the approval-numbering mechanism set out in para 4.2 and the Annex 2 illustrative captions.

Beyond these statements within the provided text, the Regulation does not list a chronological table of amendments, nor does it reproduce amendment instruments or decisions. The recorded entries on the front matter are the only explicit temporal markers present in the material provided. Where Parties or counsel need a full amendment history or the regulatory text as it stood at specific historical dates, they must consult the official ECE (United Nations Economic Commission for Europe) repository or the Agreement’s Amendment Series (as signalled by para 4.2) to retrieve specific amendment texts and dates. The Regulation’s internal mechanism for tracking amendment status via approval-number digits provides a practical identifier for which series of amendments applied to each approval at time of grant.

The provided Regulation text contains no case law, judicial decisions, administrative appeals or litigation references. The document does not name any disputes, nor does it cite decisions interpreting its provisions. Because Regulation No. 39 is an international technical instrument under the ECE Agreement framework, dispute resolution, challenges to administrative decisions, judicial review and similar litigation activity will occur, if at all, in the domestic courts or administrative tribunals of Contracting Parties or in some cases via intergovernmental or treaty dispute mechanisms of the Agreement; however, none of those mechanisms or instances are reproduced in the text.

Practically, this absence means that an interpreter seeking precedential guidance must look outside the Regulation to national case law, administrative determinations and any ECE Secretariat records concerning implementation disputes. The Regulation’s own text anticipates administrative processes like notification of withdrawal and inter-Party communications (paras 4.3, 6.2, 8.2), but it does not set out appeal rights against withdrawal or refusal of approval. Any rights of review, stay of enforcement, compensatory remedies, or standards of judicial deference will therefore be determined by domestic law governing administrative decision-making and the Agreement’s procedures, which are not included in the provided text.

For compliance officers and litigators, the key litigation risks deriving from the Regulation are administrative: challenges to a refusal to grant approval, to a withdrawal of approval, or to the administrative interpretation of whether a modification is "unlikely to have an appreciable adverse effect" or requires further testing (para 6.1.1-6.1.2). The Regulation authorises administrative discretion in those areas but does not define appeal pathways, leaving those procedural safeguards to national law. Similarly, disputes about conformity-of-production checks and the restoration steps mandated by para 7.5 will be implemented and contested under national procedural regimes. Because the document is silent on litigation, any authoritative interpretation of the Regulation in litigation must be sourced from national decisions or from bodies interpreting the Agreement and its annexed Regulations.

1. Different accuracy standards for approval versus production checks. The approval-stage accuracy relationship in para 5.3 is 0 ≤ (V1 − V2) ≤ 0.1 V2 + 4 km/h. Annex 3, which governs production conformity testing, sets wider tolerances for many vehicle categories: for M and N vehicles 0 ≤ (V1 − V2) ≤ 0.1 V2 + 6 km/h; for L3-L5 0 ≤ (V1 − V2) ≤ 0.1 V2 + 8 km/h; and for L1-L2 0 ≤ (V1 − V2) ≤ 0.1 V2 + 4 km/h. A manufacturer who designs to the approval-stage limit may still fail production checks if not attentive to category-specific Annex 3 bands, and conversely a production vehicle that passes Annex 3 might not satisfy the stricter original approval band if re-tested at approval conditions. The text separates approval and production regimes; do not conflate them (para 5.3; Annex 3).

2. Tyre selection and pressure specifics matter. "Tyres normally fitted" excludes snow tyres (para 2.3), and the test tyre pressure must be "normal running pressure" defined as the manufacturer's cold inflation pressure plus 0.2 bar (para 2.4; para 5.2.4). Using alternative tyre sizes, aftermarket tyres, or incorrect inflation undermines test validity.

3. Unladen vehicle includes a 75 kg driver. The unladen test configuration is particular: tools, spare wheel if standard, fuel, coolant, lubricant and a driver weighing 75 kg, but no passenger, optional accessories or load (para 2.6). Omitting or altering these prescribed items can change test inertia and speedometer readings.

4. Test-speed matrix depends on Vmax. The test speeds depend on the manufacturer's declared maximum design speed (Vmax) and differ across ranges (para 5.2.5). Mis-declaring Vmax or misapplying the table will result in non-compliant testing.

5. Measurement and environment tolerances are tight. Instrumentation accuracy must be ±0.5 per cent (para 5.2.6), and the reference temperature at the speedometer must be 23 ± 5 °C (para 5.2.3). If using a roller dynamometer, the roller diameter should be at least 0.4 m (para 5.2.6.2). Facilities lacking these capabilities may be unable to perform valid tests.

6. The approval-number scheme encodes amendment status. Para 4.2 requires the first two digits of the approval number to be the highest number of the series of amendments incorporated at the time of approval. Approval numbers therefore communicate regime vintage; incorrect numbering risks administrative objection and invalid cross-border recognition.

7. Marking placement and legibility are mandatory. The approval mark must be affixed in a conspicuous and easily accessible position specified on the approval form, and placed close to or on the vehicle data plate (paras 4.4.4.7). Annex 2 shows an 8 mm minimum dimension for the mark in the illustrations; para 4.6 requires indelibility. Failure to place or format the mark correctly could cause registration problems in jurisdictions that rely on the mark as the compliance signal.

For manufacturers and compliance teams, the Regulation requires three interlocking compliance pillars: type design compliance, administrative documentation and marking, and conformity of production systems and testing. Below is a practical compliance checklist mapped to the Regulation’s provisions.

1. Prepare and submit the application

• Ensure the application is lodged by the manufacturer or an accredited representative (para 3.1).
• Produce triplicate documentation describing the vehicle type with regard to tyre sizes, overall transmission ratio to the speedometer, speedometer tolerances, technical constant and range of speeds displayed (para 3.2.1). Record tyre types that are "normally fitted" and exclude snow tyres from that list (para 2.3).
• Specify the vehicle type clearly and include diagrams of the installation sized A4 or folded to A4 as required by para 4.3.

2. Provide the test vehicle and prepare it to test conditions

• Present an unladen vehicle configured as defined: running order with fuel, coolant, lubricant, tools and spare wheel if standard, and a 75 kg driver, but no additional load or optional accessories (para 2.6).
• Fit tyre types that are listed as normally fitted and set pressures to "normal running pressure", that is the manufacturer's cold pressure plus 0.2 bar (paras 2.3-2.4; para 5.2.4).
• Ensure ambient and component temperature control is available so the speedometer reference temperature can be 23 ± 5 °C during testing (para 5.2.3).

3. Execute approval tests per the Regulation

• Determine Vmax as declared by the manufacturer and apply the appropriate test speeds from the table in para 5.2.5.
• Ensure test instrumentation for true vehicle speed is accurate to ±0.5 per cent (para 5.2.6) and that the test surface is flat, dry and of sufficient adhesion, or that the roller dynamometer has a roller diameter of at least 0.4 m where applicable (paras 5.2.6.1-5.2.6.2).
• Confirm that at each test speed the speedometer reading satisfies 0 ≤ (V1 − V2) ≤ 0.1 V2 + 4 km/h for approval (para 5.3).
• Record and retain test reports in the format required by the administrative department; be prepared to supply diagrams and particulars in the Annex 1 form format when requested (para 4.3).

4. Marking and approval-number compliance