I've posted/responded in this thread in the past about my vehicles MPG. But this comment is more to do with the difference between the dash/computer reading and my hard reading after I fill up. As I may have stated before, my cars computer reading in every vehicle that I've owned with this in dash reading is usually off(reads higher) than my calculated hard reading. Often this difference can be 5-6 MPG difference, i.e., my reading is lower on every(almost every) fill up. Lately my hard reading has been off/lower by about 4-5 MPG. I mean, what's going on here?
If the vehicles computer is showing, e.g., 37.* MPG, I may typically get only ~ 35 MPG on my cell phone calculator. But on this last fill up(mostly hiwy) it read 37.7 but I only got 29.74 when I calculated on my cell phone calc. My wife's Lexus was similar as was other vehicles we've had, with the only car in our family(CIVIC in my sig) being very close in both readings.
I go by my own readings and not the cars computer.