To measure the success of a research and development project and assess its impact, an evaluation methodology has to be established. The proposed methodology in the NextETRUCK project follows best practices in validation and draws on insights from previous support projects such as CONVERGE and FESTA. It outlines a set of research hypotheses and associated goals for different innovation aspects of the project, forming the basis for evaluation. Key elements of this evaluation plan include defining Key Performance Indicators (KPIs). A total of 28 KPIs have been identified, covering areas such as vehicle and charging performance, digital tools, driver/fleet operator experiences, and market/total cost of ownership considerations. These KPIs can be measured during the demonstration and digital twin operations, using both quantitative and qualitative measures. Objective data, subjective evaluations, and inputs such as vehicle data, questionnaires, and driver interviews can all contribute to the assessment. The evaluation plan takes a structured approach, detailing each KPI’s description, assessment methods, parameters, and necessary information to address potential risks and challenges during the evaluation phase.