I'm on my third 7.3. Dealer sold you a bill of goods if they said 15 mpg city. Maybe on the highway unloaded. If you keep your foot out of it.
I've never seen 21 on the highway with any of my 7.3 10 speeds or 6.2 6 speeds. I hope you didn't base your purchase on those dealer claims.

 

I have the f350 limited, 6.7 ho diesel engine. Has about 600 miles on it. I am seeing 15 mpg in the city with it. At first mpg was very low but it improved over time.

 

Now those wishful numbers are funny. Who would of thought of a salesperson lying . 🤥🤥🤥

Go down to the 7.3 gas section and read some of the threads but watch those 4.30 rear end guys they'll tell you anything. LOL 😉

 

They Lied!!

 

My FIL's '22 with the 7.3, CCSB 4x4, would get about 18 highway, 12 city (maybe), and about 15 combined. So while OP is a little low, not outside the realm of possibility for such a big truck in the city.

 

my 7.3 can get close to that on a highway snippet but let’s be realistic. When you calculate after a mostly highway trip it’s not 18 if you’ve done any brake applications and subsequent acceleration or even a couple highway exits with merging.

they just don’t get good any gas mileage worth writing home about but that’s not what they’re really used for either

 

10ish or under in city is expected. 10 or under on long freeway trips while empty would mean something is wrong. May just need to get a few miles on it to loosen up.

I disagree with the idea these trucks are not built for fuel economy. They should not be compared to small cars but they should be compared to trucks in their class. Everyone cares (or at least they should) about fuel economy. It's silly to not want a truck, tractor, etc that is economical at its task.

 

10 MPG is pretty normal. Stop and go driving kills your fuel mileage, regardless of engine. It's just the pill you have to swallow when driving a Super Duty.

 

This is true. They're about as economical as they can get, considering they're not much better than a brick for aerodynamics. And for a brick, they get pretty decent mileage.

As for city driving, if you want something economical for that, look at a hybrid or electric - it's the only way you're going to get decent numbers in the city.

 

15 city? HA! The dealer either has no clue or lied on purpose to sell a truck. The lifetime average for the 7.3L engine in the Super Duty over the last 3 years, using millions of miles of real world owner data from Fuelly, is around 12 MPG combined. Which means city MPG is likely around 10 MPG.

 

You're right where you're going to be for the life of the truck, stop and go is hell on MPG with these trucks with the 7.3. I'm happy if I see double digit MPG while driving in city conditions. The good news is highway MPG is better but probably closer to the 15 that they said you'd get in the city....

 

I have a ‘23 7.3 with 3.73 gears. With my daily driving, 26 miles one way for work, mix of highway, city, and stop and go, I average about 12.5-13 hand calculated. Truck always shows closer to 14 on the dash, we all know that is not right. Unloaded and all highway driving around 70, best I got was about 16 hand calculated, truck said 16.5 on the dash.

 

I agree 100% with your assessment about not caring about fuel economy, it IS, silly... as... There are things you CAN do to improve your trucks MPG performance without loosing any performance. FORD doesn't really care about their trucks MPG performance because most people on here who buy these trucks, seem to go by the credo of, "you bought the wrong truck if you care about fuel economy" and they do NOT expect good fuel mileage numbers and thus... that is what they get cause FORD delivers what the consumer expects... I have increased my trucks fuel economy by 21.1% empty, 27.1% loaded, 39.3% best empty highway, driving/using it exactly the same way... so, better/higher MPG can be achieved, but who cares.

 

I get 13.5 on the outskirts of the city. Haven’t done a highway trip yet.

 

And how did you do that?