2000 BMW M COUPE Structure Problems

MY MODEL YEAR 2000 BMW Z3 M COUPE HAS SUFFERED FROM THE PROBLEM OF FAILED WELDS IN THE REAR FLOOR AREA OF THE HATCH. THE FIRST INSTANCE OCCURRED AT APPROX. 83,000 MILES, WHILE THE SECOND WAS AROUND 115,000 MILES. FORTUNATELY ON BOTH OCCASIONS I NOTICED THE PROBLEM AND HAD IT REPAIRED BEFORE THE PROBLEM BECAME SIGNIFICANT, BUT A NUMBER OF MY FRIENDS WITH Z3 M ROADSTERS, Z3 M COUPES AND Z3S HAVE EXPERIENCED THE PROBLEM WITH NEAR CATASTROPHIC RESULTS. IN ONE CASE, THE CAR IS LITERALLY TOTALLED BECAUSE THE ENTIRE REAR END TORE APART ON THE HIGHWAY. MY UNDERSTANDING IS THE FACTORY WELDS FAIL, ALLOWING MAJOR METAL PANELS TO MOVE EASILY WHICH COMPROMISES THE STRUCTURAL INTEGRITY OF THE BACK HALF OF THE CAR. ONCE THE REAR FLOOR (OR TRUNK AREA IN THE ROADSTER) FAILS, THE SWAYBAR MOUNTS AND DIFFERENTIAL MOUNTS ARE FREE TO MOVE RANDOMLY, ULTIMATELY OVERWHELMING THE REAR SUBFRAME...