What is the ideal air-fuel mixture for optimal fuel efficiency?

The ideal air-fuel mixture for optimal fuel efficiency is represented by a ratio of 14.7:1. This specific ratio is known as the stoichiometric mixture for gasoline engines, meaning it is the optimum balance of air and fuel needed for complete combustion. At this ratio, all of the fuel is burned, preventing excess fuel (rich mixture) that can lead to unburned hydrocarbons, and excessive air (lean mixture) that can lead to increased nitrogen oxides emissions and engine knocking.

In practical terms, achieving this balance allows the engine to operate efficiently, maximizing power output while minimizing waste. Deviations from this ratio can result in decreased fuel efficiency and increased emissions. As such, the stoichiometric air-fuel ratio of 14.7:1 is fundamental in automotive engineering and emissions compliance.