How to get the best MPG

It creates less of certain emissions yes the type of emissions that are related to unburnt fuel but the emissions created by the burning of the fuel could be the same or heater depending on the emissions tech on the engine

 

Minimize gap between cab and trailer. Drive slower. Keep all tires properly inflated. If owner, buy tires next time that will maximize efficiency. Don't idle or run APU needlessly.

Drive downhill when the wind is at your back and haul lighter freight.

 

Here are two articles that may help you with increasing your fuel economy:
http://www.overdriveonline.com/Smart-Driving-6/
http://www.overdriveonline.com/Smart-Driving-22/
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I suggest you start your shifts in the low range at 1100 to 1200 rpm
.for shifts in the high range start your shift at 1400 rpm.
. You really start to burn fuel like crazy starting at 1500 rpm. You need to keep that in mind.

 

Drive a company truck. My fuel bills have never been lower!.

 

unless your already doing it drop your top speed to below 65 mph freewheel down hills check your engine manufactures stats on what is the best revs for good economy you also need the right differential ratio's.

 

There's a lot of factors that affect your mpg.
I also drive a 579. Your mpg sounds very low. I average 7.8 mpg.
Shift at the LOWEST rpm that you can get away with. Accelerate gently, like there's a raw egg between your foot and the accelerator pedal. I set my cruise in the middle of my sweet spot, 1200 rpm. That happens to be 60mph. Heavy loads, head winds, hills/mountains all affect mpg. I've has as high as 11.0 loaded heavy, with a tail wind. And as low as 6.5 with a head wind.
Remember, you're big, and heavy. Don't try to keep up with the traffic at a stop light. Let them all go on. I maximize my fuel bonus, average $350.00 a month by driving MY way.
I get cussed all the time by the supertruckers that think you have to bump the speed limiter everywhere they go. Its my money, my truck, my rules!

 

I get 6.20 MPG in my truck overall.... I drive a heavy spec 386... I shift between 1500 to 1700.... BUT I will try the low shifting for sure..

 

Stay on top of your tire pressure.
I saw an advisory report on injectors. Said they were most efficient at full throttle. ??? Geesh... we're talking about a diesel here.
Cars are doing pretty good on mileage now. One thing is the ethanol fuel is bad. I use non ethanol and get over 10% better mileage. Ethanol is forced on many (Ca. for example).
In daily driving. My car is a 40mpg car. A Corolla. I've never driven over 20 minutes on the freeway with it.