...from Southwestern MS to Northeastern PA and NYC. Total of 3028.3 miles, almost entirely in HV mode: Maybe 80 miles in EV mode... Two 1200 mile drives, each starting with a full charge, ended with about 2/3 charge. I did not keep track of fuel added so, just using the Clarity's own estimation, I got 48.4 mpg. I am not displeased.
I find Clarity, in general, to be very comfortable (or as comfortable as any car) on a long trip. The adaptive cruise control and similar features make more sense to me on a long trip. Also years ago I had some back pain and got a 'back board' which forces better posture when sitting (it's cloth covered, and adds lumbar support). Anyway, on really long trips I find the board helps force me to sit in a position less likely to get 'butt pain' which is actually back pain. Anyway, that's my only add to Clarity on a 3000 plus mile trip (which I have done here out west). Like you (I think), I found the fuel economy totally impressive. I did not for example travel at lower speed to improve it- I likely went mostly 80mph where I could to reduce travel time, and I still got 40 mpg.
Based on my own road trip last year, in which I did measure fuel used, I found my Clarity's trip computer exaggerated mpg by about 10%. The longest drive that I have made was a trip from Florida to Ohio and back. The total trip distance was 2032.2 miles. I fueled a total of 8 times and used 45.8 gallons. Overall mileage was 44.4 mpg. If I subtract out the approximately 50 miles that were driven in EV mode, the gasoline mileage was still a respectable 43.3 mpg.