ultraturtle
Well-known member
My recent guess is probably incorrect. The circular part is a flange cover and closure ring to access the fuel pump:
There does not appear to be enough clearance between it and the fuel pump to add a half gallon sized plug directly to it, but does provide a large enough opening for BMW to slip in another means of displacing volume, in the same way folks drop a brick in the toilet tank to reduce the volume of each flush.
There does not appear to be enough clearance between it and the fuel pump to add a half gallon sized plug directly to it, but does provide a large enough opening for BMW to slip in another means of displacing volume, in the same way folks drop a brick in the toilet tank to reduce the volume of each flush.