AFAIU modern diesels have lower combustion temperatures in order to limit NOx formation. I imagine this comes at a cost in thermodynamic efficiency.
Similarly particle filters, catalytic converters and whatnot reduce efficiency via exhaust backpressure.
So all in all, reducing non-CO2 emissions do come at a cost in CO2 emissions (or fuel consumed, if you like). Is it as much as 15%? No idea.. And is it all worth it? I'd argue yes, old-school diesel exhaust is nasty stuff.
Similarly particle filters, catalytic converters and whatnot reduce efficiency via exhaust backpressure.
So all in all, reducing non-CO2 emissions do come at a cost in CO2 emissions (or fuel consumed, if you like). Is it as much as 15%? No idea.. And is it all worth it? I'd argue yes, old-school diesel exhaust is nasty stuff.