E60 528 fuel leak,,,I don’t see E60 to much anymore at the dealer,,,,but I have seen this now a couple of times,,,the fuel leak is coming from on top of the gas tank on the drivers side,,,,,what I found out is the white plastic top area,,,which is part of the fuel pump ,,,,,right where the fuel line lips on,,,the plastic nipple part starts to crack,,,the white plastic starts getting little hair line cracks in it and starts to seep fuel,,,the only sure way to get rid of this problem,,,,is replace the fuel pump and the short fuel feed line which goes under the car.
As you can the fuel starts to puddle on top of the fuel tank,,,,then it starts to over flow and leak on to the ground.,,you might noticed a slight fuel smell inside the car,,,,but most of the fuel smell is outside the car.
bmwtechnician 
It’s not the fuel pump, it’s the fuel filter.
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The picture is the top of the fuel tank,,,the white top piece is the top of the fuel pump which is located inside the fuel tank
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thanks for sharing but its not a fuel pump. thats the fuel filter. fuel pump is the right rear passanger side of the car and fuel pump has a electric connector.
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This looks similar to an issue in W211 Mercedes from the same era. https://static.nhtsa.gov/odi/inv/2013/INRP-EA13003-61087.pdf
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