Best mpg

[lotzagoodstuff]

I have seen near 20 mpg with my 7.3 n/a ZF 4:10s, but that's at no more than 62 miles per hour with no load. When I'm in a hurry going to Seattle and turn it up to 75 the mileage routinely gets cut nearly in half.

Careful driving and maintenance seem to make a huge difference in the IDIs.

 

[Diesel JD]

The bad news is you almost certainly have 4.10s, the good news is that your ZF5 doesn't suck up nearly as much power as an E4OD or a C6. You might think about swapping to 3.55s or 3.73s if you don't frequently tow or haul heavy. As for fuel mileage... I typically see 12-14mpg on B100 biodiesel around town and 15-17 on the highway. 2WD, C6, longbed extended cab.

 

[JwS]

With my N/A 7.3, E4OD and 4:10 gears I get a little over 16mpg going around 65 on a long trip, and if I drop the speed to 55 I've gotten 19. The rig weighs around 8000 (and it doesn't matter that much if I tow a few thousand more) and it is about 10 feet tall, so I am pushing alot of air around. I'm hoping to do a little better with the turbo, we'll see. I might go to a 3:55 rear, which should really help..
JwS