had my jeep for almost 2 yrs and just now checked the difference between what the electronic meter says and what i pump at the gas station
the meter said i was getting 21 mpg and checking gallons pumped and odometer milage said i was getting 19mpg
for those who might ask why i didn't do this sooner, this is my 4th jeep and i know you don't buy them for the gas milage

 

Mine is consistently 1 mpg more than the real mileage.

 

BOOM. Here you go. 95,000 miles worth of data from my 2012 JKU. Please know this, you need to reset the CPU each time you fill up if you want to know the MPG for the tankful. Should be obvious, but some folks don't realize you have to reset. The CPU number is just the average since the last time it was reset. The CPU on average reads 0.4mpg higher compared to hand calculation in my Jeep.

 

I reset the MPG with every tank, as well as the trip odometers. I find that my hand-calculated MPG runs anywhere from about the same as the computer to maybe 6/10 of a gallon lower than the computer. I don't bother to do the math for each tank.