Once my gauge has no bars and starts blinking there is usually about a gallon of gas left in the tank. There is also about a half a gallon or so in the filler pipe when you completely refill your tank and I am not sure if this is counted by Mitsubishi as part of the car's fuel capacity or not. I assume it isn't because I have actually filled my tank from dead-empty with more than the 9.2 gallons the manual says the car holds. What does that work out to in 'litres'? No idea...I am not a Communist so I don't use the Metric system.
As a rule for us Yanks, each bar represents approximately a gallon of gas. When none of the eight bars remain you have about a gallon of reserve fuel left in the tank. That is, IF your sender is working properly. I had to replace mine at around 130k miles because the gauge would say I had two bars of fuel left...right as the engine was coughing and sputtering to a stop after running out of fuel.