if you potter about nicly then fuel lasts a while but if you floor it, and i mean really floor it then you'll make the petrol shift.
but you might want to cheack all your lines and pump. if your is mechanical then check the oil. they can leak the petrol into the oil. if you can smell the petrol see if it burns. hell see if the oil will burn decently anyway. just in case. the only other things it could be is prehaps idle not set right or possably the mix is right off. but their only guesses.
edit.
65 miles and you used half a tank....hmm....this might be strange but top half or bottom?, i always found the fuel guage gives me weird reading with more than half a tank. it will be right full for ages then seem to drop. but thats just me.
i mean i did 160 odd miles on half a tank (998). you might want to cheack the fual tank see how much petrol there is, might be a bugged fual sender. again just a guess. i have lots of guesses.
Edited by Big_Adam, 11 July 2006 - 10:09 PM.