One and ONLY gas mileage thread please

[Dabblin]

At 9500 miles, 2012 6.2 Screw, was at 12.2 for eeeeever. Went on trip from St Louis to
Oklahoma and back. Avg speed around 75 a few passing events 90+ with plenty of umph
left... And all of a sudden the little AVG widget started moving. .. .. Up. its at 13.9 now
and as I said that's at 75. The RPM seemed to drop a bit?? Is the engine/tranny starting
to break in? Loosen up as it were?
Any one else see a marked and sudden change. That's close to a 15% increase in 500 miles.
My 5.4 Expedition never went better than 12.0 on the same trip

 

[matrix243]

Hm, trans has a learning cycle during break in but should be completed under 5k.

 

[Dabblin]

Just went on another trip aprox 250 miles. St louis to Columbia Mo. and back.
Elevation 600-700 ft ASL. 20 MPH cross winds, 80 MPH avg hit the limiter once, Wife was close to *******.. Had a ton of go for itttttt left (aprox 3000K rpm) when things stopped getting more better .......
AVG aprox 13.9---14.0 by the onboard system at the end of the outbound leg.
refueled.. hit reset......... Easier on the SKINNY pedal going home, about 70MPH avg mileage goes from 14.4 to 16.......... After 120 miles holding at 16........
A big question ???
At 40 the instant mileage drops to 14?????? Is there a sweet spot/
RPM -- BURN/TIME in Cylinder, Wind resistance, Injection tuning, Torque curves, Gearing??
40MPH=6 gear 1000RPM and more gas=14MPG At 70 its 6thGEAR 2000RPM and right at 16MPG.... 60 degrees Temp. 70% humidity/ 650' ft elevation, gusty 20MPH cross wind. ???????
Wadya Think???

Tuner/vs/Tuna?? Is there a sweet spot? Higher vs lower Speed?
Is it an averaged solution? unloaded VS rated tow Wt??
What gives ?? Love the new mileage. Might be High torque/ acceleration/
wear issues with close tolerance engines and brake-in curves??
Temps at thermostatic control levels..
or is it a dead fish, as in-- something smells ah-la Dead Fish ( IE, tuna)
Gotta love the sweet 16.......

Sorry about the broken syntax, the way the msg structure strings, trying to make it quick. Questions?

 

[Wilson]

have you calculated by hand yet?

---------- Post added at 10:20 PM ---------- Previous post was at 10:17 PM ----------

I've had mine to 25mpg before going 55 on a long trip. it will drop if you wot it a hole lot but it comes back if you return to normal driving.

 

[Dabblin]

Not yet. My truck, wife is predominate driver. She would never think to fill and hack the odometer. So the instant/trip meter onboard is the mileage I am able to track. The surprise was the quantum leap at about 10K. I have been changing oil at 3k intervals, its been dark/discolored, being full synthetic it must be from break-in of the rings. No oil loss. Guessing compression ring seating. With fully seated rings, and bearings burnished I expected some improvement. New engines in the old days 1 to 3k. New tight tolerance
engines running Synthetics, I am guessing 10k. Just trying to compare notes or add data points for others.

 

[69Mach1]

I just took a trip from South Jersey to Baltimore, MD avg about 73mph and she got 16.6mpg ....according to the dash.

 

[CrownOffroad]

Brand new truck picked up this morning in Louisburg, Kansas and driven to Denver. 650 miles and dash computed out an average of 11.9. That's a pretty much completely flat drive with some serious winds and the cruise at 77/78 mph the whole way. I'm hoping it gets better with more break in time...

 

[The Car Stereo Company]

Brand new truck picked up this morning in Louisburg, Kansas and driven to Denver. 650 miles and dash computed out an average of 11.9. That's a pretty much completely flat drive with some serious winds and the cruise at 77/78 mph the whole way. I'm hoping it gets better with more break in time...

nope. not a chance.

 

[Wilson]

Brand new truck picked up this morning in Louisburg, Kansas and driven to Denver. 650 miles and dash computed out an average of 11.9. That's a pretty much completely flat drive with some serious winds and the cruise at 77/78 mph the whole way. I'm hoping it gets better with more break in time...

havent you been reading you should not use the cruse for the first few hundreds miles. don't matter all that much these days but why not do it up wright. read the break in page. under tec page. keep it fun

 

[RAPTURR]

I avg. 13.8 mpg doing 75+ for about 45 miles everyday to work.

My 2004 FX 5.4 couldn't get better than 12 mpg.

Then again if mileage was really an issue would we own this truck. When I got under 10 one day I just chuckled to myself as I pulled into the gas station to fill up with super at $3.89 a gallon....