It's not just Mitsu, I've driven several Nissan's that will do the same thing. It says 30 miles DTE (Distance To Empty) then you look and it's ***. Being an Evo owner as soon as it gets to the 1/4 tank i find a gas station.

 

There are two stages from what I've seen (or care to test) of the gas gauge warning flash. There is the slow empty flash and the fast empty flash. Usually on the latter it takes about 13-13.5 gallons.