The claim that a catalytic converter reduces the fuel consumption of a car is not entirely accurate. Catalytic converters are primarily designed to reduce the emission of harmful pollutants from the vehicle’s exhaust, not to improve fuel efficiency.
A catalytic converter’s main function is to convert toxic pollutants, such as carbon monoxide, hydrocarbons, and nitrogen oxides, into less harmful substances through a chemical reaction. This process can slightly increase the engine’s backpressure, which may have a minor impact on fuel consumption, but it is not the converter’s primary purpose.

The fuel efficiency of a vehicle is more directly influenced by factors such as engine design, transmission, tire rolling resistance, aerodynamics, and driving behavior. Proper maintenance of these components and adjusting driving habits can have a more significant impact on a car’s fuel economy than the presence of a catalytic converter.
In summary, while a catalytic converter can have a negligible impact on fuel consumption, its primary role is to reduce the environmental impact of a vehicle’s exhaust emissions, not to improve fuel efficiency.