Crowz: you have a conceptual error in how the fuel tank works in the E53: the fuel pump will be entirely submerged until you have zero L left on the gauge. There is about 3-4L fuel that is not reported by the gauge that will keep the pump submerged down to 0.0L on the fuel gauge.

I would have to do similar research on how the other car models work but the E53 fuel tank is different from all others and there is zero benefit from the inconvenience of chopping 100 miles from your range and greatly increasing the odds of stranding yourself the first time you go a little deep into the gauge.

If you always fill up at 1/4, there is nearly a year100% chance the fuel pump will fail without you knowing it as the vast majority of pumps will just get weak vs fail completely fail. That means you can be like my wife, drive for a year with a broken pump that leaves you stranded the first time you try to get to 1/8 of a tank.

400,000 miles would be the AVERAGE life driving 62mph so if always highway miles that is not that abnormal.

Heat is not the primary concern. Especially with the x5 since if you do run it dry the farthest you can drive once the pump starts to be uncovered is about 10 miles. The brushes simply wear out. When they are worn enough the spring pressure drops the resistance rises and the power to the motor drops and it gets weaker.

The wife used to use the 1/4 tank rule her pump made it to about 128,000 I drive until the low fuel light comes on my pump is going strong at 157,000 (miles).


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2011 E70 • N55 (me)
2012 E70 • N63 (wife)