I am a little suprised that anyone thinks the guage is particularly accurate or the digital countdowns. Reading my manual suggests the tank holds 74 litres and that being the case I reckon that when the digital display goes blank ( The moment it goes under 30 miles !! ) there is a maximum of 64 litres you can squeeze in. So thats 10 litres left (Over 2 gallons ) which at gentle speeds could be 40 - 50 miles.
Trouble is once you have established that the temptation to play petrol station roulette is strong. Especially if all you come across when so close to empty is not Shell or Tescos!!
Recently discovered that the M4 between Slough and Bath has only BP stations, 3 in a b...y row.
Got 71 litres in that time, gulp,