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.