Well I get 18 with my mods just
A hint I have 250/200 full force

 

When my truck was stock I averaged 18-19.5mpg.

Now I have injectors, tuner, bigger tires, air filter, fuel regulated return and oil crossover.. About 19 highway. Average 17.5-18.5 mixed on my stock tune. My race tune gets 0.08mpg less than stock. I've never ran a full tank on my economy tune, it cuts back so much power it's annoying to drive. I'll do it one day. My truck is a base model, so no cruise control. I feel like I'd get better mileage with cruise.

 

Now I have a 96 2wd crew cab dually with Cali mirrors and a sun visor as well as lifted 2" but I have seen as much as 20 when stock and kept the rpms a 2000 or less that was about 62 mph for my 4.11 gear. (over 2000 rpm my mpg dropped 2-3) Installed a chip my city mpg went from about 14-16 to 12-14 but my hwy mpg did not suffer in fact I was able to cruise at 2000+ rpm now with no lose of mpg !!
I installed 3.55 and just did a trip from Wisconsin to Florida I was now able to cruise at 75-80+ with and averaged 17-18

 

good lord. I was looking at a 7.3 work a work rig but I'll need better mileage then that. Looks like a 6.0 it is, that sucks I really wanted to run a 7.3

 

Then run a 7.3. You may spend a tad bit more in fuel but at least u will have a great solid work truck that you don't have to dump money into for crap parts. I'd rather spend a few extra dollars topping off my 7.3 than droppung 5-6 grand dumped straight into a 6.no just for bulletproofing

 

I don't mind a bullet proofed 6.0, I was just trying to avoid going that route. But I live in wyoming where my commute may be 160+ miles just to a job site. Getting good mileage is very important. It wouldn't take long for the cost of bullet proofing a 6.0 to actually be worth it. My current truck is an 07 bullit proofed and I get roughly 23 mph, so you can see with the amount I drive that's a huge savings even after throwing 5k at it. Just sucks but it is what it is I guess.

 

The highest iv gotten in my 7.3 was 21 mpg. That was all highway driving with a chip on 100 hp performance. Fpr spring mod and 6637 intake on 265s. I wouldn't trade my 7.3 for any other diesel even for more power and economy. Gotta love a truck you can buy and not spend a penny on other than oil changes

 

And mods in stead of repairs.....

 

I've never seen a 6.0 get 23 mpgs. Is that hand calculated or lie o meter? My 7.3 has seen 22.5 on a 600 mile hwy run at 68mph, hand calculated on 140hp setting but lie o meter said 27. That was an empty bed return run.

 

I again have also not seen a 6.0 get nearly that high of mileage. Nor have I met anyone who actually liked their 6.0 (I've had several people offer to trade me their newer trucks for my 7.3, lol.)

My bosses truck says he gets like 20-22mpg on his on-board computer but when you hand calculate it, it's down to like 14-15, which seems to be the average from what I hear from people.

I see a lot of 7.3 averaging 17-19mpg. I myself get 18.7 fairly consistently now days. I think if I added cruise control it would go up quite a bit.