Originally Posted by Mr. Kite @ CleanMPG

I can get this to occur on a repeatable basis too. I had some ideas about what was going on and actually bought another ScanGauge II mainly to test this out. I wasn't able to do extensive testing since I had some issues with the SG--I returned it. Anyway, the behavior really just seems like a non-linearity in the iFCD . The gauge seems to be relatively accurate when going all the way from 0 to 100 MPG . Also, it will show 100 MPG at infinite FE . However, all the FE above ~100 MPG (I'm not exactly sure where it starts dropping) causes the iFCD to start dropping below 100 mpg.

I cannot say for absolute certainty, but I believe this behavior is just a very high FE regime--and not a 0 fuel mode. As far as propelling the vehicle, this mode is far more favorable than being in a glide--even with a few bars of assist. So, I believe fuel is being consumed in this mode.

There are many places where I see this behavior, but there is one on my commute home that is a slight decline. I'm glad to see this topic brought up again. I have never liked seeing this behavior referred to as a recalibration.