The first Japanese emission standards (for CO) appeared in 1966. During 1975-78 the standards for three types of emissions (CO, CH, NOx) were adopted, which were in effect for more than twenty years with minimal corrections. Considerably more strong regulations were consistently adopted in 2000 and 2005, and throughout 2000s there was a transition to more advanced and stringent test cycles. Actual regulations (since 2000) imply several additional grades of emissions reduction, compliance with which gives some financial benefits to the car owners.
Note, that directly compare of values from Japanese and European standards is not possible, because they are based on a completely different test cycles.
Table 1. Requirements for emissions (g/km) for passenger cars with gasoline engines.
Table 2. Emissions compliance marking examples.
In 2018 another revision of emission standards was carried out and new codes of conformity were introduced. Here is shown the part of the document relating to passenger cars with gasoline and diesel engines. A complete list including trucks, buses, as well as methanol, LPG and CNG versions can be found on the website of the ministry of transport.