6.4L Hemi mpg

I love my 2014 Ram 3500 srw 6.7 but will have to say the lie o meter is always 1.5 to 3 mpg better than hand calculated. Same thing when I had a 2005 Ram 2500 5.9. Seems to me they could make it more accurate. I thought it would be nice if they gave us a way to calibrate it.

By the way. I hand calculate everytime I fill up and I cant recall the lie o meter ever reading less than true mpg.