A modular door system provides a lower door assembly, an upper door assembly and a trim assembly. The upper door assembly is selectively removable and replaceable such that the door system is readily converted between a multiple of configurations. The trim assembly includes the interior vehicle door trim and a hinged trim portion. The hinged trim portion is defined by a trim hinge which is generally parallel to the open edge. By pivoting the hinged trim portion away from the open edge, the cavity is readily exposed for receipt of the upper door assembly. The difference in thickness of the upper door assembly is accommodated by pivoting of the hinged trim portion to permit passage of the components while still providing a seal for the cavity when the hinged trim portion is secured.