Just for fun ... interesting to see the difference between the real world data you collected and the all theoretical graph I came up with attached bellow
Assumptions I had used:
Gen-1 Insight CdA and Weight
Assumed Tire Crr of 0.01
Including 200 Lbs of fuel and driver
On Flat Level Ground
No Head or Tail Wind
Cool / comfortable day ( low 60's )
Average Humidity & pressure
Assuming average E10 mix of ~35 kwh / gallon energy content
Used Stock tire rolling circumference and gear ratios to get MPH to RPMs
Used BSFC to estimate ICE peak Possible Lean Burn Efficiency at calculated ICE RPMs.
The known other variables that I didn't think of a good way to account for are:
Vehicle electrical loads
Transmission efficiency losses
Real world Operating efficiency vs the ideal peak BSFC point at that RPM
I'm sure I missed a few as well.