According to the internationally valid automotive standard IATF 16949 (requirements for quality management systems for series and spare parts production in the automotive industry), only accredited testing laboratories (reference to ISO/IEC 17025 in IATF 16949) may be commissioned or it must be proven that the external testing laboratory meets the customer's requirements.
Beyond the requirements of ISO/IEC 17025 (or VDA 250), many OEMs have developed their own criteria for test laboratories regarding automotive release tests.
On the basis of an accreditation according to ISO/IEC 17025, test laboratories are approved/recommended by the OEMs for certain test procedures (e.g. emission according to VW 50180, emission (formaldehyde) according to BMW AA-0061, emission according to Ford WSS-M99P2222, emission according to GMW, ...).
The criteria of the OEMs are very different and range from accreditation per se (incl. interlaboratory tests etc.), participation in interlaboratory tests organised by the OEM (VW/Audi regarding emission tests), on-site expert assessment (Opel), to the classification of all release tests for the initial sampling of supplier parts (Daimler).