Subject to paragraphs 3 to 6, the certified values determined for a parent component, parent separate technical unit or parent system shall be valid, without further testing, for all family members in accordance with the family definition as set out in:

• Appendix 6 to Annex VI as regards the family concept of transmissions, torque converters, other torque transferring component and additional driveline components;

• Appendix 4 to Annex VII as regards the family concept of axles;

• Appendix 5 to Annex VIII as regards the family concept for the purposes of determining air drag.

Notwithstanding paragraph 1, for engines, the certified values for all the members of an engine family created in accordance with the family definition as set out in Appendix 3 to Annex V, shall be derived in accordance with paragraph 4, 5 and 6 of Annex V.

For tyres, a family shall consist of one tyre type only.

The CO₂ emissions and fuel consumption related properties of the parent component, parent separate technical unit or parent system shall not be better than the properties of any member of the same family.

The manufacturer shall provide the approval authority with evidence that the parent component, separate technical units or system fully represents the component family, separate technical unit family or system family.

If, in the framework of testing for the purposes of the second subparagraph of Article 16(3), the approval authority determines that the selected parent component, parent separate technical unit or parent system does not fully represent the component family, separate technical unit family or system family, an alternative reference component, separate technical units or system may be selected by the approval authority, tested and shall become a parent component, parent separate technical unit or parent system.

Upon request of the manufacturer, and subject to the agreement by the approval authority, the CO₂ emissions and fuel consumption related properties of a specific component, specific separate technical unit or specific system other than a parent component, parent separate technical unit or parent system, respectively, may be indicated in the certificate on CO₂ emissions and fuel consumption related properties of the component family, separate technical unit family or system family.

The CO₂ emissions and fuel consumption related properties of that specific component, separate technical unit or system shall be determined in accordance with Article 14.

Where the characteristics of the specific component, specific separate technical unit or specific system, in terms of CO₂ emissions and fuel consumption related properties as determined in accordance with paragraph 5, lead to higher CO₂ emissions and fuel consumption values than those of the parent component, parent separate technical unit or parent system, respectively, the manufacturer shall exclude it from the existing family, assign it to a new family and define it as the new parent component, parent separate technical unit or parent system for that family or apply for an extension of the certification pursuant to Article 18.