Motor vehicle exhaust gases. Close-up of the exhaust pipe of a motor vehicle. This is used to vent exhaust gases from the vehicle's engine, following the combustion of its fuel. The exhaust gases include carbon dioxide, carbon monoxide, and water vapour, as well as various oxides of sulphur, nitrogen and other trace components of the fuel. As well as gases, motor vehicles produce particulate pollution, microscopic grains of unburnt fuel. The fuel can be treated to reduce the amount of pollution produced, and a catalytic converter fitted to the car can help clean the exhaust gases before they are vented into the atmosphere.