I recently finished a 5 dof multibody tire/suspension/chassis model that i used lagrange's equation to solve and simulink to model. Only 2D though... It was a great learning experience. The equations are very tedious to write, easy to make mistakes, and time consuming to track down mistakes. But, in the end, not all that difficult to do. Although, during the process i found myself wondering if it was even worth it - maybe I would be better off spending my time learning Adams instead.