Mark Rinker
10-05-2010, 12:41
Today I had the unusual need to drive ~340 miles unloaded with no trailer. Filled the tank, reset all the DIC counters, and headed out with the goal of driving 68mph and observing fuel mileage.
About 110 miles into my journey, the average mileage had leveled off at 18.2, possibly it would have continued to climb, but slowly. I made a phone call, looked down, and the MPG average had dropped to 17.9...and was steadily marching downward.
REGEN.
I looked at the clock, and watched the average drop from 18.2 to 16.7. It was a full 15 minutes of dropping, before the average started once again to climb.
Made my destination, turned around and drove the 170 miles home. Upon arrival, my MPG average was at 17.2 for the entire trip. This rolling REGEN used ~1 gallon of additional fuel, by calculations using these numbers. The 2009 Duramax LMM owners manual says to expect a regen about every tankful. This means that my fuel costs just went up almost 3%, accounting only for additional regen fuel burned, before any consideration for the negative mileage impact the restrictive DPF may have over freer-flowing exhaust systems.
If we are looking at a 4% or 5% loss in overall mileage due to the DPF and regen fuel consumption, that could mean as much as $150 extra in additional fuel costs during each 10K service interval, or over $2K in additional fuel over the anticipated time of ownership... :eek:
I don't think the DPF is long for this truck, based on my first observations...and I miss my 2002 LB7, that would have easily delivered 20+mpg on the same trip, saving ~$10 in fuel - today alone.
How can it possibly make sense to burn another gallon of diesel to clean a particulate filter, designed to trap pollution from our air?
About 110 miles into my journey, the average mileage had leveled off at 18.2, possibly it would have continued to climb, but slowly. I made a phone call, looked down, and the MPG average had dropped to 17.9...and was steadily marching downward.
REGEN.
I looked at the clock, and watched the average drop from 18.2 to 16.7. It was a full 15 minutes of dropping, before the average started once again to climb.
Made my destination, turned around and drove the 170 miles home. Upon arrival, my MPG average was at 17.2 for the entire trip. This rolling REGEN used ~1 gallon of additional fuel, by calculations using these numbers. The 2009 Duramax LMM owners manual says to expect a regen about every tankful. This means that my fuel costs just went up almost 3%, accounting only for additional regen fuel burned, before any consideration for the negative mileage impact the restrictive DPF may have over freer-flowing exhaust systems.
If we are looking at a 4% or 5% loss in overall mileage due to the DPF and regen fuel consumption, that could mean as much as $150 extra in additional fuel costs during each 10K service interval, or over $2K in additional fuel over the anticipated time of ownership... :eek:
I don't think the DPF is long for this truck, based on my first observations...and I miss my 2002 LB7, that would have easily delivered 20+mpg on the same trip, saving ~$10 in fuel - today alone.
How can it possibly make sense to burn another gallon of diesel to clean a particulate filter, designed to trap pollution from our air?