...Question for folks who know diesels better, would a retrofitted urea system preserve the cars fundamental characteristics (fuel economy, performance, etc) or would there be some detrimental effect?
My understanding is that there is a tradeoff between fuel economy and emissions. I suspect if they tune it to reduce emissions, then the fuel economy will go down.
Basically, I think they need to run the fuel/air mixture more rich so that the temps are higher in the emissions reduction components in the exhaust system.
The industry is being mandated for better fuel economy AND lower emissions. VW picked one...