Just don't want to ask the guy to fill the tank and end up covered in fuel. I'd prefere to eastimate the current contents and ask for "X" litres or "Y' amount of currency.
That sounds about right the first time mine started blinking the Est. Range said 80kms.On mine, when it gets to the last bar and it starts blinking, that's when there's about 4 liters (1 gallon) of fuel left. Or at least that's what the pump suggests when i fill it up.