[paulgb]

I think the intent is less about the CO2 emissions as about the air quality that people have to breathe (hence a stricter standard in some locations).

I don’t know about measurable effects but I hate when I pass a long-idling truck and can taste it in the air.

[amanaplanacanal]

Diesel exhaust is horrifying. Why aren't diesel engines subject to the same pollution regulations as the rest of us?