Ford F250 7.3l Gas “Godzilla” Mileage report

[Lamar]

Just wanted to post some of my long trip fuel mileage results for those who may be interested.

This is for a 2020 Ford F250 with the 7.3 Liter gas engine: 4WD Crew Cab Standard Bed, 10 speed auto, and 3.55 gears.

Towing a 2020 Globetrotter 27FBT with a 3” lift @ typically close to max 7600 lbs.

From Atlanta to Denver and back in July 2021:
normal grade gas 87 octane for the entire trip. I did not use the 85 they have in CO. Going to Denver I got an average of 9.5 mpg. I had moderate cross winds on I-70. I got the same mileage on return trip with the same cross winds.

From Atlanta to San Diego in June 2022.
Going to San Diego I used 87 octane until OK when I switched to premium for the rest of the trip. The headwinds were awful at probably 25 to 30mph starting in Arkansas. Fuel mileage per tank in OK, TX, and part of NM had dropped from about 9.6 to 8 mpg due to the winds. It got better on the following days and I was getting 11.5 and even 12 on a tank or two along part of the I-17 and I-8 legs. The final tally arriving in San Diego was 9.0 mpg for the trip.

For the return trip from San Diego to Atlanta the winds weren’t as bad and were from the rear right mostly while on I-40. Return mileage for the whole distance was 10.4 mpg which I was happy with.

I feel like the premium gas helped with mileage snd performance, especially in the mountains. I’d like to hear other’s opinions.

[Lamar]

….. Speed was between 65 and 70 mph for both trips.

[Daytonacoupe]

Originally Posted by Lamar

Just wanted to post some of my long trip fuel mileage results for those who may be interested.

This is for a 2020 Ford F250 with the 7.3 Liter gas engine: 4WD Crew Cab Standard Bed, 10 speed auto, and 3.55 gears.

Towing a 2020 Globetrotter 27FBT with a 3” lift @ typically close to max 7600 lbs.

From Atlanta to Denver and back in July 2021:
normal grade gas 87 octane for the entire trip. I did not use the 85 they have in CO. Going to Denver I got an average of 9.5 mpg. I had moderate cross winds on I-70. I got the same mileage on return trip with the same cross winds.

From Atlanta to San Diego in June 2022.
Going to San Diego I used 87 octane until OK when I switched to premium for the rest of the trip. The headwinds were awful at probably 25 to 30mph starting in Arkansas. Fuel mileage per tank in OK, TX, and part of NM had dropped from about 9.6 to 8 mpg due to the winds. It got better on the following days and I was getting 11.5 and even 12 on a tank or two along part of the I-17 and I-8 legs. The final tally arriving in San Diego was 9.0 mpg for the trip.

For the return trip from San Diego to Atlanta the winds weren’t as bad and were from the rear right mostly while on I-40. Return mileage for the whole distance was 10.4 mpg which I was happy with.

I feel like the premium gas helped with mileage and performance, especially in the mountains. I’d like to hear other’s opinions.

Your variance between premium and regular IMHO is subtle and could be attributed to many factors; road surface, weather, altitude, winds, traffic patterns...... I'm curious what your mileage is when not towing. I've got a Silverado 2500 extended cab 4x4 with the 8.1L gas hog and Allison transmission. I tow a 34' Limited and the difference in fuel consumption between trailer / no trailer is negligible. I used to own a U1300L diesel Unimog (5 ton) that got better fuel mileage. The 2500 is not great on gas but is well suited to its' purpose and used accordingly. Cheers!

[Dennis C]

I think you would have been fine running 85 octane fuel in Colorado if your truck normally runs on 87 octane in other parts of the country. The high elevation in Colorado results in less air density and therefore higher octane fuels aren’t required. I’ve heard that running higher octane fuels at higher elevations can actually be less efficient than lower octane fuels, but I can’t verify this. I’ll add that this isn’t necessarily the case for vehicles with forced induction like a turbocharger or a supercharger. In my normally aspirated GMC truck, 85 octane works well. In my turbocharged vehicle, I run 91 octane which is the premium fuel available in Colorado.

I think that most modern vehicles with electronic fuel injection will automatically adapt to the fuel that you use and to external factors like altitude.

I think that things like wind and steep grades impact mileage much more than octane rating.

[Slimpockets]

Hello fellow Georgia native! I have done 1 trip in my 3.5 XLT MPP 4x4. 11 mpg on the way from Atlanta to Charleston @65. It got closer to 12 at 60 but your becoming a road hazard at that speed. I thought long and hard about getting that 7.3 truck but settled for the 150. I’m about to head up to Wisconsin so I will get 2000 miles towing. Will try to report back the Mpg’s . What is your payload? Mine came in at 2500#.

[Keith S]

Hi folks,
We just returned from a trip from Southern Ontario to Harrisburg, PA making a large loop through PA and back up to the border.
We drove approx 1118 miles and used only low octane fuel.
Our rig is a 23’ 2019 FC FBQ and our TV is 2018 F-150 5.0 Coyote engine. About 400HP.

We averaged 13.7 MPG.
I take it easy. No hard acceleration and I drift on the downhill runs. Also, I keep my speed at about 60 MPH

The funny thing in comparison, if I drive around town, the truck alone uses about the same amount of gas.
We don’t use the truck much other then towing the trailer as we have a small Mazda CX3 which is very fuel efficient.

Gas prices up here in Canada are ridiculous. Almost $CAD 8.00 gallon. What a rip off.

Regards,
Keith Stamper.

[Gansett]

I thank you for your mileage data. I have a very similar set up with my 2022. I travel with my Airstream at about 7,200 lbs.
I am in the middle of a two month trip out to Yellowstone from RHODE Island. I am getting about 11.5 mpg so far. RI to MN it was more like 10 mpg but I had strong head winds. Up at higher elevations it got much better, about 12 mpg. We had to pivot from Yellowstone NP due to flooding, so we went to Moab UT. Got about 12 mpg. Now on way back and whole trip average 11.2 mpg.
I drive at 65 most of the time, all tires at recommended psi, and use 87/85 octane fuel. I feel 85 is suitable for higher elevations. It is my understanding there is no energy difference between grades. Octane is a measure of what temperature the gas explodes in the cylinder. Turbos and very high performance engines need high octane so gas won’t pre-ignite before the spark plug fires. In old days, engines would “diesel” when turned off because the hot engine was igniting the gas in the cylinder. If your engine requires high octane and you use a low octagon, you may lose power because engine management de-tunes output to compensate. Love to hear other points of view, other mpg data.

[Daquenzer]

Interesting. I have an F150 towing a 28' and get better mpgs. And when I'm not towing I get 20 to 22mpgs with 17.5 mpgs for every day driving. You would think that big engine would do better than that while towing.

I would be interested in what the mpgs pulling are on the smaller Ford engine in the 3/4 ton class. I think it is about a 6.2L engine.

Also would be interested in what Dodge's 6.2L Hemi does with a similar trailer.

[1StreamDream]

I have a 2021 7.3L with the 4.30 rear end, towing a 25’ RBT flying cloud, generally around 6500lbs, and I’m doing well if I can avg 10mpg towing, even in the flatland Midwest. More common for me to be in the 9 range, and wind or mountains take it even lower, but I do love the power I have. I have to stay at or below ~67 mph to see 10mpg. Love the truck, I ordered it the way I wanted it, no regrets here but with $6/gal gas I do wonder how much difference/improvement the 3.73 rear end would make (that was the only other rear end gear option available when I was ordering).

[Troser]

I have a 2022 F250 with the Godzilla motor. I tow a 28RB International Signature fulltime. We were out for 7 months and averaged 11.2 mpg. The greatest change I made to achieve that mileage was not to exceed 62 mph. This was the highest speed I could maintain while simultaneously enabling the transmission to stay in 10th gear the greatest amount of time.
Happy trails!

[davidrrand]

All very interesting! I have thought of upgrading to 250 + 7.3. Current truck is 2015 F150 4X4 Lariat SuperCab 6.5 bed with 5.0 V8, pillar payload is 2031 lbs. and tow 2016 FC25, about 7000+ lbs. Just completed fourth trip to the Rockies since 2016 from NW Georgia. This trip was about 6500 miles, used 511 gallons of gas, overall mileage 12.8 and 45 nights on the trip, all per the trip computer. About 15-20% of the miles were unhooked exploring so towing mileage was easily less than 11 mpg. Normally use 87 here in GA and used 85 out west and noticed no difference in performance. Get around 18 mpg unhooked around my NW GA mountain home and 21 mpg on 70 mph interstate trips without trailers. I think the 7.3 would work for me towing and the bigger mpg loss would be around home and on trips non towing. Sound likes a good option if I ever decide to take more stuff!

[Lamar]

Originally Posted by Daytonacoupe

Your variance between premium and regular IMHO is subtle and could be attributed to many factors; road surface, weather, altitude, winds, traffic patterns...... I'm curious what your mileage is when not towing. I've got a Silverado 2500 extended cab 4x4 with the 8.1L gas hog and Allison transmission. I tow a 34' Limited and the difference in fuel consumption between trailer / no trailer is negligible. I used to own a U1300L diesel Unimog (5 ton) that got better fuel mileage. The 2500 is not great on gas but is well suited to its' purpose and used accordingly. Cheers!

I have an 2001 Chevy 2500 8.1 L with 4.10 gears too. That thing IS a gas hog. I get 7.5 to 8.2 mpg towing the AS. About 10 to 12 mpg on the interstate at 70 mph with no trailer. My F250 gets 15 to 17 mpg on the interstate with no trailer.

[davidrrand]

P.S. I usually drive the speed limit on highways and interstates. On the way out on I 40 was the exception through OK, TX and NM where we had sustained winds of 35+ mph for two days. Drove 60-65 with semi passing on the left at 70-75, with pull/push effect on the trailer. Caused the driver side SS segment protector to pull the middle top bracket that is riveted to the AS skin from the trailer, leaving four holes. Noticed the segment protector vibrating violently in rear view and pulled over. Removed the support bracket from the last rivet and supported the protector with a stuffed towel between the protector and the airstream that stabilized it. Later used a section of foam pool noodle to stabilized and finished the trip with no further damage except a destroyed Michelin tire (trailer) in Gallup NM that was replaced with a Cooper at Pep Boys and on the way to Moab from Kodachrome a "falling rock" went through the curbside plexiglass window protector but saved the window. Repaired with Gorilla tap inside and outside. Sorry to hi-jack but keep and eye on the segment protector brackets. If they get loose, re-rivet before you have them pulled out like mine did!

[Scott S]

If the increase is due only to the change in octane (and that is doubtful), it is highly unlikely that increase in what you paid for the premium was covered by the decrease in fuel used.

[Lamar]

Wow, yeah, thanks for the info on the protector. I haven’t checked them. I will do that for sure. We had the same sort of trip here. Had a lounge widow break on I-22 near Jasper AL on the Saturday we left. Didn’t know about it until we stopped for lunch. Taped it up. Called nearby (relatively) AS dealers but no one had a replacement. Luckily AS of New Mexico had the exact glass we needed on order and it was due to be delivered about the time we would be passing through Albuquerque. They squeezed us into the schedule and did a great job. Done in less than 2 hours. Had to fix my trailer brakes in San Diego as the two right brakes had the wires pulled apart somewhere along the way. Also rtv’ed some galley cabinet screws in that kept backing out. Then the flat tire a quarter mile before the Kingman exit on the way back. We luckily found a tire dealer that did rv’s right at the exit. Bought 4 new Carlisles and discovered two shocks were missing the nuts. Zip Dee Relax awning quit working while we were at the Grand Canyon and fixed a dinette table that rattled loose on I-40.

Originally Posted by davidrrand

P.S. I usually drive the speed limit on highways and interstates. On the way out on I 40 was the exception through OK, TX and NM where we had sustained winds of 35+ mph for two days. Drove 60-65 with semi passing on the left at 70-75, with pull/push effect on the trailer. Caused the driver side SS segment protector to pull the middle top bracket that is riveted to the AS skin from the trailer, leaving four holes. Noticed the segment protector vibrating violently in rear view and pulled over. Removed the support bracket from the last rivet and supported the protector with a stuffed towel between the protector and the airstream that stabilized it. Later used a section of foam pool noodle to stabilized and finished the trip with no further damage except a destroyed Michelin tire (trailer) in Gallup NM that was replaced with a Cooper at Pep Boys and on the way to Moab from Kodachrome a "falling rock" went through the curbside plexiglass window protector but saved the window. Repaired with Gorilla tap inside and outside. Sorry to hi-jack but keep and eye on the segment protector brackets. If they get loose, re-rivet before you have them pulled out like mine did!

[dmcgaugh]

2021 F350 with 7.3 and 3.73s towing a 2017 30RB international and all of you all in the 9-10 range jives with what I’m getting.

I run premium and regularly see 9.8 and 9.9 and can eek out 10.0 if I keep it at 60 MPH (it’s like it’s mocking me refusing to get double-digits most of the time).

Interestingly, I live in Washington state and my trips up and over the pass are nearly the same as up and down I-5, so isn’t impacted much by climbing.

[Mikebrady62]

I have a 2018 Chevy 1/2 ton with the 6.2L engine. I do not notice any milage gain by using the 91 octane fuel but when I use the 87 octane there is a definite ping when going up hill. I typically tow at 70 mph unless it is very windy, then down around 65 mph. We do a 1 month aprox. 6000 mile trip each year and our overall MPG is right at 10. Some days with a significant headwind it's as low as 7.5 and other days as high as 12.7 but each of those are uncommon. I use the higher octane when towing because I think my truck will last longer not for better mileage.

[davidrrand]

Originally Posted by Lamar

Wow, yeah, thanks for the info on the protector. I haven’t checked them. I will do that for sure. We had the same sort of trip here. Had a lounge widow break on I-22 near Jasper AL on the Saturday we left. Didn’t know about it until we stopped for lunch. Taped it up. Called nearby (relatively) AS dealers but no one had a replacement. Luckily AS of New Mexico had the exact glass we needed on order and it was due to be delivered about the time we would be passing through Albuquerque. They squeezed us into the schedule and did a great job. Done in less than 2 hours. Had to fix my trailer brakes in San Diego as the two right brakes had the wires pulled apart somewhere along the way. Also rtv’ed some galley cabinet screws in that kept backing out. Then the flat tire a quarter mile before the Kingman exit on the way back. We luckily found a tire dealer that did rv’s right at the exit. Bought 4 new Carlisles and discovered two shocks were missing the nuts. Zip Dee Relax awning quit working while we were at the Grand Canyon and fixed a dinette table that rattled loose on I-40.

Similar experiences! We spent the night in ALBQ and had the owner of the Airstream dealership look at our damage. Sold us a new attachment bracket and said it could be patched but he was booked solid (it was the weekend, too) and we had reservations the next couple of nights in Sedona before hitting the Grand Canyon. We've heard other favorable reports about this dealership in this forum and wish we had the time to get it fixed but were on a schedule with family.

Sent photos to the dealer in Norcross upon our return and interestingly they said as a four rivet dealer, Airstream would not let them do patch work, only full panel replacement. Contacted JC and they provided a quote for patch and full panel replacement, was a little cheaper than Norcross but could not get to it until January 2023. Not real interested in JC in January! Will keep looking for other options. Glad you like your F250!

[Dallashayes]

Thanks for all the information everyone. We just traded our Tundra for an F250 with the 7.3 and are getting ready to head out for about two weeks. I’m very interested to see how this truck handles the FC 26U and the MPG. Report forthcoming once we return.

[Lamar]

Originally Posted by Troser

I have a 2022 F250 with the Godzilla motor. I tow a 28RB International Signature fulltime. We were out for 7 months and averaged 11.2 mpg. The greatest change I made to achieve that mileage was not to exceed 62 mph. This was the highest speed I could maintain while simultaneously enabling the transmission to stay in 10th gear the greatest amount of time.
Happy trails!

Agreed. Driving to keep it in the higher gears is best for economy. I’m genuinely impressed by this truck’s ability to tow in those OD gears. As long as I manage the rate at which I apply throttle it stays in and pulls in those OD gears better than I would have thought possible. I’ve been extremely happy with this F250. I would buy it again in a heartbeat.