What gas comes out the exhaust pipe of a car and is a result of combustion?

What gas comes out the exhaust pipe of a car and is a result of combustion?
Complete combustion from a car results in CO2 (carbon dioxide) and H2O (water) as the byproducts. However, car engines are not perfect converters of fuel into CO2 and H2O. The engine's incomplete combustion results in CO (carbon monoxide) and the other particulates and impurities in the fuel can create various (often toxic) types of byproducts that can lead to things like smog (Nitrogen plays a big part in this as car combustion often lead to the creation of NOx).
Catalytic converters are made to decrease the three main pollutants in automobile exhaust: an oxidising reaction converts carbon monoxide (CO) and unburned hydrocarbons (HC), and a reduction reaction converts oxides of nitrogen (NOx) to produce carbon dioxide (CO2), nitrogen (N2), and water (H2O).