I get 19 MPG empty and 14 MPG when hauling this with 2 adults 4 kids, 6 bikes and their toys

 

I've run a lot of gasoline and diesel fuel through vehicles and various pieces of equipment and never had any issues with water in the fuel. Yes, I do drain the water separator and/or fuel tank on things that have those valves, and never have gotten any water out. The worst is a little bit of sediment. I buy almost all of my fuel from two stations including the fuel put in portable tanks for equipment, and store no fuel, vehicles, or equipment outside where it can get rained on.

Diesels are more expensive to maintain as everything costs more but at least the pre-emissions ones last a lot longer than gas engines do. Quite a few diesel engines are sleeved and can be easily and repeatedly rebuilt, although none of the engines we are talking about here are sleeved from the factory. I generally get somewhere around 13 miles per gallon or so with my '99 7.3 F-450 empty (although it's rarely empty) and 8.5-9 miles per gallon fully loaded, the exact mileage heavily dependent on road speed and the amount of stop and go. A friend has an '02 or '03 V10 F-550 and he generally gets 2-3 fewer miles per gallon than my F-450.

 

I have both, identical trucks except pano roof, right down to the rims and tires, both driven by me, ignoring towing miles, 80% highway.

7.3 Gas - 11MPG
6.7 Diesel - 18MPG

I was shocked as well, driven 70-75MPH mostly highway. Crazy.

 

Just returned from a round trip from North Carolina through VA, WV, OH to Michigan and back driving 99% Interstates and 4 lane highways using cruise set at speed limits mostly 55MPH to 70MPH, with a few traffic delays. We had no more than 1,000 pounds loaded in the 2024 F-350 Gas 6.8L 2WD with stock street tires. We have towed a 5,000 pound travel trailer with the F-350 so far, but not on a very long trip. Will check towing MPG on a longer trip. I have not compared gallons used to miles driven, only used computer so far. The speedometer reads the same as the Garmin GPS speed.

 

Best case scenario mileage there, probably showing ~1mpg high, as the readout usually does. Interesting!

 

I have a 7.3 gas crew cab dually with 4.30 gears and Ive never only got 11mpg empty even driving 80mph I still get high 12s.

 

About 11mpg vs 16mpg diesel

& 9 gallons of def last about 6k miles not towing,

 

Something is off, my 22 7.3 gas gets 10-11mpg driving around town. On the highway at 70-75 I get 16-18mpg when empty, a few times hit close to 20mpg when the wind was with me. My newer 26 is a 4.30 rear end but even then it gets over 10 around town with short trips and everything,

 

Sure, flash in the pan you can get that, this is a fleet truck with data, 11mpg is the number.

Using brief snippets of mileage is just delusional.

 

I guess I will just have to trust my log book that tracks my miles and fuel up data over Sir "Hemi" from the internet.

If you think your stated non-towing fuel usage is normal at 11mpg 80% highway, well, learn to drive better.

 

I just went through this scenario last year and most recently this week.

I was in the market for a F-250 last year and debated between gas and diesel. I would only require occasional towing of 22' enclosed car trailer and didn't want the "extra costs" of the diesel, so I convinced myself the gasser was the best choice for me with my use case. I purchased a 2020 F-250 7.3 w/10 Spd AT. As stated in a few posts, the MPG can vary greatly (especially depending on the gear ratio) and my highway mileage was pretty decent unloaded, even driving 70-75, being 17+, but when towing...FORGET IT! Unless you are willing to drive 55-60, you are stopping every 2.5 hrs. to fill up. I drove from VA to FL at 70 and my mileage was high 6 to 7 MPG. When I slowed to 65, it went to almost 8. I did two trips this past year and in the middle of the second trip, I was looking to buy a diesel. I had no luck making a deal in FL, so when I got home, I started looking again. I just took delivery of a '22 F-350 6.7L. The impact was noticed immediately on the 5-hour trip home when I got 22+ on the way home driving 70-75 compared the trip there of 17.

Another anecdotal point, a local dealer let me take a 2020 F-350 LB 6.7 for an "extended" test drive over the weekend, so I took the time to hook up the trailer and do some "testing". These were very short test, but enough to prove to me that replacing my current gasser with a diesel was going to be the right choice for me; at 70 I was getting about 10.5 MPG and at 65 about 12.4 MPG. The number would obviously settle over a period of time, but they aren't going to settle at 7 or 8.

In the end, the LB was too long for my needs, so I got the SB, which I'm sure will do the same, if not better, having the same gear.

I hope my experience will help someone who in the same boat and save them a year of buying, driving, selling/trading and having to buy the correct truck for their use case.