Just an update! 4600 miles, I finally got over 8mpg! I have done some muffler work on my '05 and my last tankful gave me a mpg of 9.64! THATS MORE LIKE IT!! I removed the stock muffler and put on a FM 70. I worked it at least one way during this last fillup and was loaded at about 14,000 gross lb's I did 4 deliveriers on this tankful so I was definatley impressed. Much better than the 6mpg I was averaging earlier. At about 3800 miles I to0k a load of mulch and some lumber to my sisters on the interstate and I averaged 7.6 mpg round trip; approx. 300 miles with half of that weighing 15k +/- and traveling an average of 80mph.

 

labwillow is driving the heaviest configuration of any of us empty.

If you understand the physics of drag from tires, wind resistance and then look at where he is from (all hills and mountains) then you might just get an appreciation for how significant posting a 7.6mpg report at 80mph with half the trip being heavy weight.

 

After 1800 miles of highway and city driving the 05 F250 Supercab 4x4 V10/6spd is up to 12.5 avg for highway and city, and more like 13.2 on the highway. Around town it really seems to drink the fuel down, but that might be due to the BSEG factor. On the highway it just rolls along towing 6500lbs like its nothing, and speed will constantly creep up without knowing it if Im not running the cruise control. I have a feeling my mileage will be up to 14 unloaded on the highway soon.

 

I've noticed that my mileage goes DOWN on the highway- it just cruises SO nice above 90!

 

nisiar - Great, just great, and so true. I've been laughing for the last 5 minutes!

 

new 05 sd V10 first 224 miles town and slow driving some highway with cruise I got 11.5 for new and tight not bad. I am not a hard driver but have pushed the V10 some and it is just great. I am running empty right now and no expressway highway so set the cruise at 60.

 

Dyno Testin: Don't know about Ford but I toured the Cummins plant a few years back where they build the 5.9. When that engine comes off the assembly line they hook it to the dyno and as soon as OP comes up they run it to full throttle. Yeah guys, I know this is a FORD forum.
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