Bummer on running out of gas, it is also one of my big fears when going for record distance on the NAH or any car. On your comment of never going above 45mph, I would have to disagree with you. The charging of the HV battery would kill your FE. I feel a combination of the right commute and using the ICE and EV mode at the right time is key. I am also curious, IAN33 I have read in some of your posts that your display reads around 38 MPG, have you calculated by hand, and is the hand calcs and display closer than many of us are getting. Eg I can get a tank which the display shows 46 mpg but the hand calcs are around 43. Incidentally, my recent commute to North Pole NY 650+ miles, the display showed 39.5 and my hand calcs were dead on 39.51002. It may be that the EV mode results in some error.

I believe the computer, on average, is going to be more accurate then hand calculations.

All cars have gas in the line and odometer error and all gas pump displays have gas in the line and display error. Between the two it would be a miracle if the margin of error wasn't at least + or - 3%. The computer uses an algorithm to determine MPG and would always be the same amount off if the other two were consistent, but none of them are.

You could use an advanced GPS to check on your milage error, but you would need to use the same pump every time to figure out the pump error. These are some of the reasons why Consumer Reports always attaches their own back wheel odometer when they test cars and why the government constantly monitors pumps.