For my MY 2000, M-5 transmission Insight, as a non-hybrid, from Denton, TX, to Oklahoma City, OK and back, at a constant 65-mph, with air conditioning ON, the car returned 52-mpg for the roundtrip ( what my 1984 CRX got at 55-mph, without air conditioning ).
The 'green' Insight, is turbocharged, if I remember correctly. Julian could verify that.
At the February 2, 2019 visit, the owner conveyed to me that he had witnessed up to 80-mpg. I do not recall all of the particulars. He was in from out of state, and as happy as I was for the visit, I didn't want to keep him from quality family time.
His plan was to cosmetically restore the tail, and have it color-matched to the 'new' Insight.
Jim's design feature, which allowed for the use of the rear hatch really impressed me, as did all of it.