Validation is a critical component of model-based design (MBD). Without it, regardless of the level of model verification, neither the accuracy nor the domain of applicability of the models is known. Thus, it is risky to base design decisions on the predictions of unvalidated models. The Integrated Vehicle Energy Technology (INVENT) program is planning a series of hardware experiments that will be used to validate a large set of unit-, subsystem-, and system-level models. Although validating such a large number of interacting models is a large task, it provides an excellent opportunity to test the limits of MBD. For INVENT, a Verification and Validation Plan (VVP) has been created to implement many relevant aspects of both verification and validation: it describes several methods and approaches, identifies roles and responsibilities for the diverse group of team members, specifies the process flow to be followed by the team, provides reporting standards for each step in the process flow, and suggests ways to determine the level of model validation required depending on the model purpose. This paper describes the VVP and highlights steps taken to date toward its implementation in INVENT.