Ford 6.2 gas vs 7.3 gas highway gas milage

I am the owner of a one week old Thor Coleman 19CM with 7.3 engine on it and during the last week I drove it from AR to CA.
Despite being the tiniest possible C class when we hit the strong windy conditions I was making 9mpg average on the flats and 8 to 8,5 on the hills.
Then when we hit the flats again and on a calm evening hours from Blythe to LA we were averaging 10 to 10,5mpg when I set the cruise control at 70mph.

After a while I decided to slow down and set the cruise control to 60mpg and it went up to 11mpg.

Today for the first time on a calm day I was driving back to home on flat roads and decided to cruise at 55mph and it went up to 11.4...
That was my best so far during the 2300 miles in my first week.

To be honest when I first started the engine it scared me. I thought it sounded like a big muscle car! Still think it's a little overkill for a 19' long mini-C class but what do I know?

This is the mileage display on my work truck, a 2009 F-450 with the 6.4L diesel for power.

If I calculate the mileage on paper it always comes out 1 mpg lower than the display, the same with my Lincoln. I think ford does that intentionally to try and make us feel good. :)

362 mile round trip, all freeway and empty.

specta wrote:


This is the mileage display on my work truck, a 2009 F-450 with the 6.4L diesel for power.

If I calculate the mileage on paper it always comes out 1 mpg lower than the display, the same with my Lincoln. I think ford does that intentionally to try and make us feel good. :)

362 mile round trip, all freeway and empty.

That's not all that bad considering..I had an old 454 that never got better than in the 8's and 6-8 loaded and the weight didn't matter..

jaycocreek wrote:


That's not all that bad considering..I had an old 454 that never got better than in the 8's and 6-8 loaded and the weight didn't matter..

I disagree.
As Specta says -real value is 1 mpg lower, what considering mostly empty truck is very lousy for diesel.
My Dually averaged real 12 mpg with 6000 lb camper on it.
This is what my cluster said after Alaskan trip. Pretty close to fuelly calculations.

^Because the old 6.4 Flowerjoke is a turd of a motor. Heck, even Ford who gave the 6.0 about 3 more years than it should have, dumped the 6.4 after only 2 years.

jaycocreek wrote:


That's not all that bad considering..I had an old 454 that never got better than in the 8's and 6-8 loaded and the weight didn't matter..

It s 390 CI diesel. I would expect better than 8.7 mpg empty on the HWY.

It was never known for its mpg..

8-12 mpg
6.4pstroker

Most 6.4s get b/w 8-12 mpg stock.Apr 5, 2011
www.powerstrokenation.com › how...
How many mpg should a 6.4 diesel get | Ford Power Stroke Nation

jaycocreek wrote:
It was never known for its mpg..

8-12 mpg
6.4pstroker

Most 6.4s get b/w 8-12 mpg stock.Apr 5, 2011
www.powerstrokenation.com › how...
How many mpg should a 6.4 diesel get | Ford Power Stroke Nation

Its a slug no matter how you look at it.
This truck has had the engine replaced twice with new factory 6.4s at the dealer.

I know the lease company has spent over $8000 repairing this one over the last two years in less than 10,000 miles.

I marvel that they have kept it this long.

I don’t think many people run 6.4s stock, but my F450 with 4.30s got better than that stock. I expect most SRWs with 3.73s got much better unless you are talking higher MPH. I didn’t buy mine for MPG.

$8000 is a lot, but not outrageous considering how much new trucks are. Other than DPF issues that no longer happen, mine has had zero issues. I could have bought a new one for 40K more when I bought mine 6 years ago which would have been double the price.

jimh425 wrote:
I don’t think many people run 6.4s stock, but my F450 with 4.30s got better than that stock. I expect most SRWs with 3.73s got much better unless you are talking higher MPH. I didn’t buy mine for MPG.

$8000 is a lot, but not outrageous considering how much new trucks are. Other than DPF issues that no longer happen, mine has had zero issues. I could have bought a new one for 40K more when I bought mine 6 years ago which would have been double the price.

I'm sure there are lots of good ones out there and I'm glad that you have one of them.

I'm sure that this one is actually the oddball, especially with the engine having been replaced twice. this is only the second year that I've used it and its only during the winter months.

I used to tow the snow cat with a 1-ton Chevy and I much prefer towing it with this F-450. Longer wheel base, its heavier and has better brakes and when the going get rough the limited slip or what ever it has in the rear diff helps a lot.

This one has the 4.88 gears but for one reason ort another speed doesn't seem to affect the MPG.

Since it came out of the shop about 8 months ago it runs as good as it ever has. I think someone who knew how to fix it finally got to work on it.