Be a bit wary of the Scanguage numbers - it's an indication but not an accurate measure so if that's what you're using, I'd check your gas receipts against miles driven for a ballpark reasonability check.

I have one also but have yet to get an accurate read despite all the calibration activities. All my MPG reports are based on calculation using fuel consumed vs. miles driven, mostly off the same pump with the same brand of gas.

I record our details here and let the website compute the FE. Would be great if you would add your details too as the more data points the better the idea we all have of how these perform under what conditions. As I mentioned, we're cold start, short suburban 90% of the time so that kills us. What's your typical pattern?