I ran mine down to "0" miles before I could fuel up. It took 9.6 gallons. The tank is 11.9 gallons, so the question is: Will the tank actually hold 11.9 gallons of fuel or is it 11.9 gallons by volume ? All modern fuel tanks have an air space for the EVAP system.
The very first post of this long thread doesn't directly answer your question, but provides other detail that will help get you the answer. [WARNING] Running out of gas (Gen III) | PriusChat
On my Avalon hybrid I have about a 550 mile range, when the miles to empty is at 100 I start looking for a gas station, by 50 miles I will have filled up. With this range I have no desire to test the limits.
I have always been told it is not a good idea to run your car low on gas because the fuel pump is cooled by gasoline but never heard any scientific proof. I have only ran out of gas a couple of times in my life, once was on purpose .
I hope that you adjust these figures according to the situation ... gas150km.jpg by fuzzy1 posted Oct 14, 2012 at 7:01 PM DSCN1334gas106c.jpg by fuzzy1 posted Mar 22, 2014 at 10:15 AM gas163mi2.jpg by fuzzy1 posted Mar 13, 2014 at 9:27 PM