Lewis,

As I had mentioned in my previous post, the ScanGauge shows high fuel consumption as the engine warms up. Once fully warmed up, the fuel consumption drops to around .2 to .3 gallons per hour at idle.

-When cylinder inactivation kicks in, the mileage shown by MPG indicator on the ScanGauge tends to jump perhaps 25 to 60 percent.
-When autostop kicks in, fuel consumption drops to 0 GPH (because the gas engine is off)
-As the vehicle slows and the batteries are charging, fuel consumption doesn't drop below .2 GPH and the instantaneous MPG shown is sometimes over 100MPG.
-When accelerating, instantaneous mileage is low (sometimes sub 10MPG).

As the car warms up, some hybrid functionality starts kicking in before other functionality, so there is not exactly any one moment when the car "goes hybrid". When hybrid functionality kicks in, whatever guages you have displayed on the ScanGauges still display. There is no little message that pops up or anything saying that the car has gone into hybrid mode.

My typical mileage is just 6 miles to and from work, though I did take it for a longer highway drive last weekend. According to the instrument panel, I drove a round trip of 82.0 miles at 35.2 MPG. According to the ScanGuage, I drove 80 miles at 36.2 MPG and burned 2.2 gallons of fuel.
So the ScanGuage and the Accord Hybrid's instrument panel were fairly close, though not exactly matching. This was a highway drive to a shopping mall and I had to spend 15-20 minutes driving slowly around the mall parking lot to find a place to park which lowered my mileage somewhat.

I have a StreetPilot 2610 GPS in the car so I'm planning on seeing the trip distance it records when I get a chance for comparison purposes, since the GPS is highly accurate. Last weekend I had the GPS and the ScanGauge both on the dash and my recollection is that I was getting speed readings along the lines of the following on the highway:
GPS: 60.0 miles per hour
Accord Hybrid's Analog Speedometer: ~59-60 miles per hour
ScanGuage: ~58 miles per hour

Thus far, my experience has been that the ScanGauge seems to be fairly accurate on my Hybrid Accord though you can see that there is some variation in numbers.