These rules are used in the certification of vehicles, including in the field of ecology (euro standards). These standards are designed to limit the content of harmful substances (levels of hydrocarbons, nitrogen oxides, carbon monoxide and particulate matter) in exhaust gases of gasoline and diesel engines of vehicles.
The introduction of new, more "strict" environmental standards makes it necessary to make changes to the design of the car. The changes mainly concern the exhaust system and engine management system. These changes include the installation of additional catalytic converters and oxygen concentration sensors.
There are currently five Euro standards (Euro 1 - Euro 5). Each subsequent standard significantly tightens the emission standards for pollutants. The Russian Federation has currently introduced the Euro 3 standard for new cars, and the Euro 5 standard has been introduced in 27 EU countries.
| Standard | Year of introduction | |
| Countries of the European Union | Russia | |
| Euro 1 | 1992 | |
| Euro 2 | 1995 | 2006 |
| Euro 3 | 1999 | 2008 |
| Euro 4 | 2005 | |
| Euro 5 | 2009 | |
The introduction of Euro standards imposes certain requirements on the technical condition of the vehicle, engine design, and quality of operating fluids. For example, the quality of motor oil must correspond to the environmental class of the engine, and the amount of various substances contained in automobile fuel is regulated.