This paper presents the development and implementation of a real-time Driver-in-the-Loop (DiL) simulation platform for pedelec drivetrain validation. The system architecture integrates a Digital Driver Twin—a biomechanical rider model executed on industrial SEW MOVI-C servo controllers— with a MATLAB/Simulink Real-Time environment running on Speedgoat target hardware. Deterministic Ethernet communication enables synchronized data exchange at 1 kHz sampling rates between the simulation host and distributed actuator nodes. The Digital Driver Twin generates physiologically realistic pedal torque profiles incorporating phase-shifted bilateral actuation and negative recovery torque components. Unlike conventional test approaches prescribing fixed trajectories, the proposed architecture enables emergent vehicle dynamics through closed-loop interaction between the virtual rider model, physical test specimen, and simulated environment. Experimental validation through 20,000 km endurance testing demonstrates the system's capability to reproduce field-representative failure modes unattainable with traditional constant-load protocols. The implementation showcases the convergence of industrial automation technology with model based design methodologies for advanced Hardware-in-the-Loop applications.