For over a century, the automobile has represented freedom, power, and the thrill of mechanical mastery. The connection between driver, machine, and road defined what it meant to own and love a car. But in today’s digital era, a different trend is unfolding. Cars are no longer just machines designed to take us from point A to point B. Increasingly, they resemble something else entirely: smartphones on wheels.
Lean burning increases mileage, but produces nitrous oxides.
Rich burning produces carbon monoxide, which eventually converts to CO2 in the atmosphere.
Unit for unit, NOx emissions are 265 times as damaging as CO/CO2.
https://scied.ucar.edu/learning-zone/how-climate-works/some-greenhouse-gases-are-stronger-others
To successfully convert NOx, catalytic converters need a stoichiometric or slightly rich fuel/air mixture to the engine.
https://en.m.wikipedia.org/wiki/Catalytic_converter