Originally Posted by jonnyvtec
I best go down to the calibration cell and tell them... to stop the fuel systems team packaging a urea injection system into the MY15 cars as it doesnt reduce NOx according to some dude on the internet.
Instead of being a sarcastic bitty you could just ASK me, "What's the urea for then?"
And I would respond: "Urea is Not used to neutralize NOx. It is used to burn-off the Particulate Matter captured in the exhaust filter via a chemical reaction." And then I would further elaborate: "The NOx in diesels is neutralized by the catalytic converter. Same way all gasoline cars have neutralized NOx since the 70s."
Some diesels don't use urea at all. They just fill-up their PM filter, and then you change the filter, same way you change your air and oil filter periodically. Last I heard that is the method Honda is using.
Final random thought:
Gasoline cars also produce soot.
Rub your hand around the rear of an old car's tailpipe.
They should have PM filters too, but lawmakers haven't mandated (yet).