I'm from the 7.3 forum but have a buddy that has a 08 king ranch. It is F350 single rear tires. He get 13mph if he baby it. It doesn't sound right to me. The truck is stock. Only has 13,900 miles on it. What are you guys getting? Are they any mods he can do to improve it?Thanks for the help!

-Doug

 

About right for the 6.4L EPA choked Desiel.

 

Almost every other thread on here is about poor mileage on the 6.4. Yeah that sounds about right. Tell him to thank the EPA for the giant filter in his exhaust and the regens that kill mileage.

 

I get 12.5 steady empty on my 08 F350 Drw, 4.10 gears

sam

 

My 08 F -350, CC,LB,4X4,4;10 diff weighs 9250lbs ready to tow a 14K plus 5th wheel. It does in the 13's stop and go city driving and 15/17 interstate at 62/65 mph.. 10/11 towing. I do not thing that is bad for a truck that big that weighs that much.

 

I agree with everyone here; 13 is pretty typical for these engines.

I only have 8,600 on mine and I'll get somewhere between 11-12 city, 15-17 highway. I always drive with MPGs in mind and almost never go above 65 MPH. Highest I've ever done was 18.5.

 

I just traded my '08 F-250 King Ranch for an F-150 King. The diesel got terrible mileage. . .most of the time around 11 mpg.

 

I made 3 trips from Ohio to Washington D.C. in December. All 3 trips were pretty even meaning no trailers or heavy loads, just the family and luggage. Ohio is 'carpenters dream' flat but W.V. and PA have plenty of hills.

I tried to baby it on trip 1. Kept it at 65 except when the limit was 70 and then I did 70. I controlled the speed myself and got 13.7 cummulative for the trip.

For trip 2 I used the cruise control and got 12.8. Really disappointed with that one.

For trip 3 I decided to quit worrying about mpg and make good time. I ran 75-80 (even more in some stretches) and I got 14.5

This goes against all logic and the only theory I have is that it was easier for the truck to maintain speed through the hills at 80 than it was 65-70. Maybe constant boost is better than fluctuating boost?? I dont really know the answer for it. I didnt compare temps, wind speeds, or anything else like that but it seems like even if there was a variable like that the mpg would at least be comparable regardless of the speed.

 

Caprang, it's amazing how you got so much better MPGs at 75-80!

However I suspect it had more to do with wind conditions than anything else. Remember that the single largest detriment to fuel economy at highway speeds is wind resistance. Wind resistance goes up by the square as speed increases linearly. For example there is 4 times the wind resistence at 80 than there is at 40, but you're only covering ground twice as fast. This is the primary reason why high speeds are inefficient.

Now with that being said, if you have, say, a 20 MPH tailwind your wind resistance will be equivalent to only travelling 60 MPH. Sure your RPMs would be higher but you'd still have less drag on your truck than you normally would, so your MPGs would still be great. Now figure you're doing 65 with that same 20 MPH wind coming towards you instead at your back. Now your truck is slogging through the air like it's going 85 but it's only travelling 65! Your MPGs would be AWFUL.

I never tracked this with my pickup but I have with my work truck. Even loaded to over 70,000 lbs I can get nearly 8 MPGs with a significant tailwind. With a headwind I may only get 5.5-6. This is a 30% difference!