New diesel midsize (Chevrolet Cruze)

[greyghost]

I don't know for sure with cars but heavy truck engines have improved fuel mileage w/ urea injection as the designers are able to decrease EGR. For them urea is purchased as a premix and simply added to the "urea tank". Sensors insure you do not operate w/o urea.

[cRiPpLe_rOoStEr]

Originally Posted by greyghost

I don't know for sure with cars but heavy truck engines have improved fuel mileage w/ urea injection as the designers are able to decrease EGR.

EGR is the worst for Diesels. It increases the generation of particulate matter, denoting a decreasement at the fuel-efficiency