1. The yellow standard vehicle is the abbreviation of the vehicle with high pollution emissions. It is a gasoline vehicle that does not even meet the national I emission standard, or a diesel vehicle that does not meet the national III emission standard. Because it is affixed with a yellow environmental protection mark, it is called a yellow standard vehicle. 2. The yellow standard vehicles have large emissions, high concentration and poor emission stability. Due to the backward exhaust emission control technology, the exhaust emissions of these vehicles cannot meet the Euro 1 standard, and the emissions are equivalent to 5 to 10 times of new vehicles. 3. The identification of yellow standard vehicles is based on the exhaust emissions. Here we talk about the national I standard and national III standard. 4. The Light Vehicle Emission Limits and Measurement Methods (I) implemented in 2001 in China is equivalent to the Euro I standard. The Light Vehicle Emission Limits and Measurement Methods (III) implemented in 2007 is equivalent to the Euro III standard. 5. Therefore, the emission standard of country I is that carbon monoxide shall not exceed 3.16 g km. Hydrocarbons shall not exceed 1.13 g km, of which the particulate matter standard for diesel vehicles shall not exceed 0.18 g km, and the durability requirement shall be 50000 km. The national III emission standard is that hydrocarbons shall not exceed 0.66%. Carbon monoxide shall not exceed 2.1% Particulates shall not exceed 0.1% Nitrogen oxides shall not exceed 5%.