Although from all these posts, this may be pointless, I'm doing a little experiment with my current tank. For the length of this tank, I'm leaving the butt-warmers off, the A/C and/or Heating off and the radio/CD player off. I'm going to limit gunning my HiHy to very rare occasions (although this is probably the hardest part). I'm even altering my commute to work to take an expressway instead of the freeway. Basically, eliminate as many excuses as possible for that Energy Monitor from being so far off from my manual calculations.

I don't really buy the reasoning that the discrepancies between the EM and manual calcs are due to nuances in filling up the tank, because the EM has been consistently higher than the manual calculation for every tank I've filled up. If the discrepancies were due to fill up nuances, I would have expected some of the comparisons to show EM reporting lower than the manual calculation.

So far, the EM shows 28.1 mpg at about 100 miles into this tank. We shall see... Based on prior discrepancies, this should translate into a manual calculation of about 26.6 mpg.