This International Standard 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 3,5t, 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.