So far, with about a half dozen fill ups, I've found the onboard computer to be with in two tenths of what the old school math is telling me. I don't know what others are experiencing but my computer seems pretty accurate.

 

More aggressive driving = less accurate, less aggressive driving = more accurate.

 

I agree with above, Ive only filled up twice but the computer is dead on. avg 18 combined but 22-22.7 on highway. but im easy on the pedal. Only have a 1000 miles on mine

 

Mine is usually off anywhere from .5 to 1.5 mpg. The 11's may be more accurate..... I fill-up the same way every time and hand calculate it and compare it to the computer, then reset the computer every fill-up.

In my truck, (you can see what it is in the sig) Averaged 16.3 over 8800 miles with high's of 17.6 and a low of 14.7. Been averaging 16.9 consistently from the beginning of March.

 

Pretty good numbers for a 4x4. I filled-up yesterday morning and averaged 18.303 mpg in combined driving. The Avg Comp read 19.2 mpg. I did have a few day's where some spirited driving was accomplished to pass in traffic.

 

i think its safe to say, with the 11's and 5.0 , were gonna see 17-18 city and 19-22 highway consisently once they break in and your easy on the pedal.

im curious to see what happens with bigger tires & level kits.

I plan on putting wheels/tires on after spring. I'll have a few thousand on the truck so i should be able to see the difference.

coming from 10-11mpg on my f250 - 17/18 is like a dream now

 

Yeah I can't complain really and thats with winter blend gas.....

 

getting 16-17 mpgs with my 5.0 4x4 scab. Only 350 miles on it so far.

 

Filled up again today (doing a ton of driving the past week, things will calm down after Monday) 17.3 mpg hand calculated and 18.2 on the computer..... 17.3 I'll take it for the way I drive and the fact that its a 4wd....

The hard part is deciding what engine to get in my next truck in 12 or 13 (or wait for the next gen) EB or 6.2L?

 

This is why I like liters, it's the same unit of measure in every country

 

the pcm uses torque managment gone crazy. a tune will eliminate torque managment and allow the real power to shine.