DPF fuel consumtion

[JimT]

Just to add, DEF is used to reduce NOx emissions, while the DPF's purpose is to catch and burn soot. EGR was, and still is, the primary way these engines attempt to control NOx (along with lower engine RPM's) by reducing the combustion temperature and as a result the exhaust temperature. The DEF is secondary when the NOx levels are still too high to meet the newer requirements. While it's true that regens for the DPF will result in increased NOx output, it's not the only factor. The amount of fuel burned and the amount of DEF needed to reduce NOx can, and will, vary depending on engine condition, operation and efficiency. Tracking the relationship between EGT's and DEF usage might be more consistent than the relationship to fuel, but I'm not aware of a way to do that.

Even narrowing it down to DEF used only during regens, as you mentioned, can and will vary wildly depending on type of regen, soot load at the time of regen and efficiency of the DOC and the regen.

Looking back at my fuel/DEF records, it seems I pumped about 5 gallons DEF for every 300ish gallons of fuel. Though it wasn't an exact relationship between the two. As Rawze said, you could probably find common averages based on segment/usage characteristics and of course an over all industry average. But it would only be an average and wouldn't be accurate for any specific truck. It's like saying the average family has 2.4 kids (or whatever), it doesn't have any relevance to the individual.