The development of entire car bodies benefits from simulations, especially if they are performed at an early stage of development because they lower the costs for required car body modifications. This paper focuses on a dip paint simulation and describes the simulation process as an e-coat (electric coating) thickness simulation which considers gas bubbles, drainage and buoyancy forces. This paper points out the advantages of this technology by explaining the theory behind this. A new hydrodynamic method is used which performs about 1000 times faster as standard computational fluid dynamics (CFD) solvers. In addition, this method allows executing the computation on standard desktop machines, i.e. no high performance computer (HPC) is needed.In addition we introduce a simple method to calculate the static buoyancy forces of arbitrary homogeneous objects and a simple model movement of an engine hood induced by buoyancy and drag forces.