ISO 3929:2003 specifies methods for the direct measurement of the concentration of exhaust gas emissions from road vehicles during inspection or maintenance. It is applicable to vehicles having a maximum authorized total mass (ISO-M08, as defined in ISO 1176) not exceeding 3,5 t, equipped with controlled ignition engines, but excluding those supplied with a fuel/oil mixture (with or without automatic mixer). The methods can be used, either totally or partially, for periodic inspections in official garages, official roadside checks (e.g. by police) and maintenance and diagnostic operations.