What is the function of adding urea to a car?

[ZacharyFitz]

Adding urea to a car primarily serves the function of reducing vehicle pollution. Urea has a catalytic function that enables nitrogen oxides to undergo a chemical reaction, converting them into non-toxic and harmless nitrogen and water, thereby purifying the exhaust gases. Automotive urea is a liquid used in SCR (Selective Catalytic Reduction) technology. The need to add urea applies to vehicles with diesel engines because diesel engines emit harmful nitrogen oxide gases, which cause environmental pollution. Long-term inhalation of these exhaust gases poses significant harm to human health. To mitigate this hazard, vehicles with diesel engines are required to add urea. Urea has a catalytic function; when it encounters nitrogen oxides, it triggers a chemical reaction, converting nitrogen oxides into nitrogen and water, which are then emitted.