Just for comparision, I did a 2400 mile trip back in August. I Ran through the different HD300 tunes & checked mileage on each during the trip. I got the best mileage on the stock file, but all tunes were within 1MPG of each other. Both times I ran the HD300 stock file my average speed was lower at between 55 & 65 MPH due to road conditions. Tow, Street & Performance tunes were all run on flat prairie highways at 65 to 75 MPH. I wouldn't say weather conditions played into any of the mileage figures, Athough there were times when head winds would have been in the 10 to 15 MPH range.
Truck is 2010 F350 with 3.55 gears & 37" tires. Engine RPM ran between about 1450 & 1700 depending on speed. Speedo is calibrated dead on according to test sections along the highways & about 3 different electronic speed read outs in construction zones. I thought I would see a little higher mileage figures on the flat Alberta Roads, but it is what it is. The only thing I really noticed between the tunes was my back bumper corner was black after running the Performance tune
All the tunes cruising @ 70 MPH ran 13 to 15% throttle, 25 to 30 % engine load, 9 to 12 lbs boost & 640F to 680F on the pre turbo pyro.
Here is what I got hand calculated to US Gallons.
HD300-Stock = Ran 476 miles = 16.39MPG
HD300-Tow = Ran 387 miles = 15.56MPG
HD300-Street= Ran 472 miles = 15.81MPG
HD300-Performance= Ran 325 miles= 15.53MPG
HD300-Stock= Ran 524 miles= 16.45MPG
I ran the last 200 miles home on the Tow tune again but haven't filled up to see what that figured at.
What kind of mileage results do you see with the Mild Group of tunes compared to the HD 300 tunes on your truck?