NOx is not Nitrous Oxide and is not short for Nitrous Oxide. Nitrous Oxide is specifically N2O. NOx refers to both Nitric Oxide (NO) and Nitrogen Dioxide (NO2), both of which are far, far more damaging to health and atmosphere than N2O. NOx emissions are the reason diesel is generally nonexistent in US passenger vehicles - not even great mpg numbers have sufficiently-low NOx emissions.
Even if it included N2O, using nomenclature with a variable like “NOx” and grouping it all together as one inert byproduct vastly underrepresents harm. Imagine if you referred to another group as “COx” but saying it’s relatively inert and easily detected by way of a burning lung sensation but feeds plants so it’s not all bad because Carbon Dioxide (CO2) has that effect. Carbon Monoxide (CO) is completely left out of that description and will silently kill you.