The number of vehicles for the preliminary investigation test shall be five. For the preliminary investigation test results, if the arithmetic mean of the test results for any of the regulated air pollutant exceeds the emissions standards limit, or the test results of the same regulated air pollutant from three or more testing vehicle exceed the emissions standards limit, then the preliminary test of that engine family or vehicle model shall be deemed as fail to meet the emissions standards. However, for vehicles applicable to Article 5 of the emission standards effective on September 1, 2019, the preliminary investigation test related stipulations shall be handled in accordance with provisions stipulated in Appendix 1.Appendix 1.pdf