Mr_D thank you for the link.
I have to admit that the graph on page 35 surprised me and is totally off the chart.
If there is any logic to that, than someone who has a fuel economy of 3.5 mpg at 20K should expect 6 mpg at 140K - this is ABSURD!
So my V10 itasca gave me 7.8 gpm @27K and if I drive it to 140K I will be getting around 15 gpm!
That would be FANTASTIC - but would never happend!
Yesterday at work I hooked up my laptop to one of the units equipped with Cummins ISL 8,9L engine:
ECM DISTANCE 239858.4 miles
Engine average load 29.00 pecent
Fuel used 66250.0 gal
TRIP CINCE LAST RESET
Average fuel economy 3.61 gpm
Idle fuel used 549.0 gal
Drive fuel used 59983.9 gal
Drive fuel economy 3.997 gal
I think that this is pretty much self explanatory.