I’d just chime in that emissions controls are about particulates NOx, SOx and other pollutants, but not CO2. Combustion of a gallon of diesel will create the same volume of CO2. That’s not to say that those other pollutants aren’t important, they’re damaging to human health, but when I hear “green” I think CO2.
The emissions weren't the issue; they just kept replacing the engine with newer ones - the Ford one they were using at the end had a Euro VI version so they could have kept using that.
The issues were more around safety (both passenger and pedestrian) and not being able to sell it in many countries because it can't have an airbag fitted (I think there was an ergonomics reason it wasn't possible).
