The TC48 project is developing a state-of-the-art, exceptionally low cost, 48V Plug-in hybrid electric (PHEV) demonstration drivetrain suitable for electrically powered urban driving, hybrid operation, and internal combustion engine powered high speed motoring. This paper explains the motivation for the project, and presents the layout options considered and the rationale by which these were reduced.The vehicle simulation model used to evaluate the layout options is described and discussed. The modelling work was used in order to support and justify the design choices made. The design of the vehicle's control systems is discussed, presenting simulation results. The physical embodiment of the design is not reported in this paper.The paper describes analysis of small vehicles in the marketplace, including aspects of range and cost, leading to the justification for the specification of the TC48 system. The design aspects of the TC48 powertrain system are discussed, particularly the sizing of the motor and battery pack.Aspects of the TC48 powertrain system and their fit with the donor vehicle, a Vauxhall Adam equipped with manual transmission, are described. The disposition of the major system components, the battery pack and switched reluctance motor is described.The control loops for the clutch control and torque allocation are presented. The MATLAB/Simscape models of the vehicle are presented. The simulation results for these control systems are presented and discussed.