What I am suggesting --when the tank is almost empty, fill it up and see how many gallons it takes from what it reads on the pump. That will tell you if the tank was near empty or not, based on the amount of fuel your tank will hold when it is full and how much it took to actually fill it.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas