WLTP 2026 Correction: What Vehicle Manufacturers Must Review

Key data

Vehicle manufacturers and testing laboratories operating under the WLTP (Worldwide Harmonised Light Vehicles Test Procedure) must review their type approval procedures following the publication of an error correction to the Regulation (EU) 2017/1151, identified as CELEX:32017R1151R(06) and published on 05/05/2026.

This type of correction—technically called an errata—does not introduce new regulation, but does amend technical provisions that were already in force. When errors affect calculations, test parameters or reference values, any type approval process based on incorrect data is at risk of not complying with the officially valid values.

What does this regulation establish?

Regulation (EU) 2017/1151 complements Directive 2007/46/EC on type approval of motor vehicles, specifically regarding emissions and fuel consumption. The WLTP procedure it regulates was designed to measure CO2 emissions and consumption under more realistic conditions than the previous measurement cycle (NEDC).

The published correction—the sixth errata of the regulation, as indicated by the R(06) code—affects specific technical provisions of the procedure. Based on available data, the elements that may be modified are:

• CO2 emissions calculations used in type approval
• Test parameters applied during WLTP tests
• Reference values used in the type approval process

The exact details of each correction are found in the official text published on EUR-Lex under reference CELEX:32017R1151R(06). Errata have retroactive effect from the publication of the text they correct, meaning that the corrected values are those that should be considered valid from the origin.

Economic and operational impact

The impact of a technical correction in the WLTP regulation is not minor. The emissions values approved under this procedure have direct consequences on several fronts:

• Fleet emissions target compliance: Manufacturers have average CO2 emissions targets per fleet set by the EU. If approved values change due to the correction, the fleet's compliance position may be altered.
• Validity of ongoing approvals: Type approval processes being processed with values prior to the correction may need to be reviewed or re-executed.
• Credibility with authorities: Approval bodies and laboratories that have issued certifications based on incorrect parameters must assess whether it is necessary to correct documentation already issued.
• Internal review costs: The review of procedures, recalculation of values and updating of technical documentation generates direct operating costs for approval departments.

The entry into force date is not specified in the publication, which adds urgency to consulting the official text to determine from what point the corrected values apply.

Who does it affect?

• Light vehicle manufacturers that approve models under the WLTP procedure in the EU, including passenger cars and light commercial vehicles
• Technical approval bodies authorized to issue type approvals in EU Member States
• Testing laboratories that perform WLTP tests to measure CO2 emissions and fuel consumption
• Approval and regulatory departments of automotive groups with operations in Europe
• Vehicle importers that manage individual or small series type approval processes

Practical example

A vehicle manufacturer has a model in the type approval process whose CO2 emissions value measured under WLTP is 118 g/km according to the calculation parameters prior to the correction.

If the errata corrects one of the calculation factors applied during the test—for example, a rolling resistance coefficient or an energy reference value—the final approved value could vary. Depending on the direction of the correction, that same vehicle could be approved with a value higher or lower than initially calculated.

In practical terms: if the corrected value exceeds the threshold that determines the model's contribution to the manufacturer's fleet average, the impact can be directly transferred to the calculation of fleet CO2 target compliance, with the economic consequences this implies in terms of possible European regulatory penalties.

This scenario requires the approval department to verify, model by model, whether any of the corrected parameters affect their already performed or ongoing tests.

What should companies do now?

1. Access the official text of the correction on EUR-Lex (CELEX:32017R1151R(06)) and identify exactly which technical provisions have been corrected: emissions calculations, test parameters or reference values.
2. Review ongoing type approval processes to determine whether any of the corrected parameters have been applied in tests already performed or in process.
3. Evaluate the impact on already issued approvals in coordination with the corresponding approval body, especially if the approved CO2 values may be altered.
4. Update internal test procedures in laboratories to incorporate the corrected values as mandatory reference from the date established by the correction.
5. Confirm the application date of the correction, given that it is not specified in the publication. Contact the national approval body or consult the official text directly to determine from when the corrected values apply.
6. Document the reviews performed to demonstrate to the authorities that internal procedures are aligned with the corrected regulation.