One problem related to gas tank strap has been reported for the 1999 BMW 3 Series. The most recently reported issues are listed below.
The BMW 323i ( BMW e46 ) fuel tank strap, which holds the fuel tank in place, detached from the car body. This is a strap holding the fuel tank in place. The 4 spot welds that hold the strap to the car body failed. Note, the fuel tank is held in place by this strap.