Here is the secret advice.

I personally idle all the time, but I have a pre egr motor. I wouldn't be idling with newer motors. I also cruise at speed limit, be it 65 or 70

 

Haven't seen the hourmeter. Just got the truck so haven't done the dash menu yet.

 

Our company doesn't believe in APUs, so we have clean idle stuff. You heard Dave complain his APU wouldn't cool. When I park at truck stops almost everyone idles. Gets hot in the south.

 

I’ve been idling for the last 2 weeks with an 2001 ISX pulling fully loaded flatbed freight and I averaged 6.4 mpg, California and Midwest.

Since I’ve owned it I’m at 6.53 for the last 3 years. I do have a gen I run sometimes but not the last 2 weeks. I usualy run around 65 but I have been running speed limit up to 70 (governed) for the last 2 weeks.
All hand calculated.

 

My actual mpg is 7.96
A few weeks ago I went without my apu , as I was holding off to get it to a particular shop. I idled every night for nearly 2 weeks. As far as the speed limit ,I drive it.
There is no elected official on this truck.
I do limit myself to 70 though. I prefer to keep my cash where I can spend it , instead of blowing it out the stack.

 

Can't do that on this truck it has anti siphon on the tanks. You can't get an accurate gallon measurement.
Ecm and ifta reports run with in a few point of each other.

No offense to you but , your original statment just doesn't hold water.