Please never use petrol till its empty.....it is possible that some impurities have been now sucked up by pump and might cause issues later.
What was the avg u were gettin before doing this 'tank empty' trial.
Usually people calc avg by full tank method...they check km driven till when the reserve fuel light gets On and then refill........since cultus doesnt have that light, i would suggest to refill when the gauge has reached exactly at 'E' line....the gauge goes further down frm that but i think its no need to go till there and that E line is easy to remember and be safe.
I usually do this...whatever fuel i put in (atleast 10ltrs), i refill always at that E line...note the km run...and calc the avg....i am getting 13km/ltr these days...i put in Rs1500, 13.10ltr fuel and drive 180kms on that.
