Can Someone Verify The 2017 Prius Fuel Tank Capacty. ALso The Farthest You Have Gone On A Full Tank

Our gas price fluctuates on a weekly cycle. Filling up on Tuesday evening is key.
The farthest I've gone is well over 800km and I was quite impressed because I'd only had the car for about a month (bought it when it came off a 2 year lease from someone who leased it while waiting for his Tesla to arrive). Coming back from a holiday in Newfoundland with the car filled with me, a tent, my hammock frame and hammock, my folding bike, my packraft (with paddle, lifejacket etc) other clothing and camp kitchen and cooler etc.
I filled up in Edmonston, New Brunswick heading for home in Kingston, Ontario. Into the wind and slightly uphill, I guess, although mostly flat after I got past Quebec City. I prefer not filling up in Quebec due to their higher gas taxes but I wasn't driving particularly hypermiley. When getting near Montreal I realized that I might make it to Ontario without refueling so I dropped the adaptive cruise to 2 bars and got behind a truck (here they're speed limited to about 106kph). Not only did I get to Ontario but I got home and didn't fill up until the next day after doing a lot of running around putting stuff back in my storage locker and getting groceries etc. That tank got me 844 km with a consumption of 3.6 litres/100km. I've since had an 871km tank, but usually fill up earlier (usually to phase correctly with the local price cycle. I would like to see my first 1 Mm tank someday, but that will have to wait until warm weather returns.
BTW, that trip took me up and down the west coast of Nfld and out and back for a total of 7504 km with consumption total of 4.0 l/100km. I never got close to that in my 2009 Prius, that my son now drives.

 

Just looked at my log. My farthest on a full tank was 577 miles (929km). Every gas fill takes a detour (yes, even just for turning off the road and pull up to a pump) and time, so I usually wait until the tank gets really low. There were times I rolled into a gas station with the remaining miles-to-empty in the single digit. Don't worry; It's all calculated. I push it that far on my commute route so I know I'll for sure get it filled before it goes down to 0. I am always curious though what would happen when the reading goes to 0. Does it give me ANY buffer at all?

 

Hard to know - but my suspicion is that there are still a litre or 3 in the tank. And TOYOTA, VW, SUBARU, ROLLS ROYCE - aren't going to tell us - because they don't want us to run out. One of my cars a long time back would take 55 litres regularly in a "supposedly 50 litre" tank.

Trivia - what I did find was:

 

Assuming Gen4 tank and gauge is identical to PRIME's, you still have ~2 gallons left when you first see the gas empty light comes on. I have driven over 100 miles after DTE reached 0 miles, but I could fill only a bit over 10 gallons into the 11.3 gal capacity tank, meaning still ~1 gal left in the tank.

 

Previous Prius generations have a significant buffer, disclosed in the Owner's Manual, and very many of us have repeatedly gone past DTE=0. It would be a shock to many of us if Gen4 didn't do the same. See just the first post of this long Gen3 thread: [WARNING] Running out of gas (Gen III) | PriusChat

OTOH, some other brands have different practices. E.g. my Subaru Forester has NO buffer beyond its equivalent to DTE=0. But it does have multiple stages of low fuel warnings, more prominent and colorful than in my Gen3 Prius, beginning with more than 2 gallons remaining. And its Distance Remaining display quits showing any number at all, just dashes, at about 30 miles remaining. It takes a greater degree of driver disengagement to miss than in a Prius.

As a test, I was going to run the Forester dry, but then wussed out at the last fuel station before a long stretch, too long for the fuel can brought along for recovery. It ran out a couple seconds after I pulled up to the pump, before shutting off the ignition, as I reached for my fuel logbook. The refill amount was just a few hundredths of a gallon different than the stated tank capacity.