The FEM (Finite Element Method) is a proven tool for solving vehicle structural mechanics problems. Because the Body-In-White (BIW) structure, see Figure 1, can be represented by a finite element model, the vehicle body panel deflection, deformation, and twisting induced by special cause variation in the build process can be predicted. This capability may aid in finding the root cause of some build problems.A current production T-top vehicle experienced a severe roof drop problem in prototype build. The roof drop at the back light header averaged from three to fifteen millimeters. Since the roof directly affected the hatch opening, this would have caused serious waterleak, wind noise, hatch fit and operating problems if it were not corrected prior to production. This roof drop problem is one example of robogate clamping/assembly processes that may be simulated and investigated using the FEM method.