One of the other things those CO2 regulations did is push companies towards producing and selling diesel cars that emitted less CO2 but more other pollutants like NO2 and particulates that caused direct and immediate harm. Which lead to dieselgate and then this: "Compliance has gotten harder for automakers as consumers have shifted toward gasoline cars, which emit comparatively more CO2, following Volkswagen AG’s diesel-emissions scandal that first erupted in 2015."

So I guess this isn't so much a footgun moment as a whole series of them.