What is your DTE after fill-up? (Gen 5)

My "DTE" is constantly updating indicating my ultimate miles till empty will be higher than first estimated. This is the problem with the logic; if your driving efficiency changes from tank to tank, your DTE will be useless. Last tank I had some very long idle times w/ AC running, in hot weather (for my dog). This tank I am being diligent to not have those wasteful moments so I can "see what I can get". I'm on track to get about 680 miles on this tank. But my DTE currently estimates 630.10 remaining. I didn't remember to take a photo of my DTE after last fill-up, but I'm guessing it was around 600 miles, because that's what I got last tank.