Purpose This paper outlines a complex simulation model for parallel-hybrid diesel railcars with hydrodynamic power transmission. It contributes to the discussion concerning whether a hydrostatic recuperation system can be an alternative to electric systems using double-layer capacitors or flywheels. The paper focusses on a hybrid system with realistic parameters concerning mass, power, and energy content that should be applicable to both existing and newly built vehicles. Methods A simulation process that is based on the 1-d-multidomain simulation tool Imagine.Lab AMESim is presented. The simulation comprises a conventional and an alternative drive train as well as the longitudinal dynamics of the vehicle along with the control of the vehicle motion. Energy-efficient driving techniques and timetable restrictions are taken into account when comparing train runs of different drivetrain configurations. Results Simulations based on real route data for eight different railway lines show a reduction of fuel consumption between 5 and 16 % due to the hydrostatic recuperation of energy. Station spacing and mean line gradients prove to be important line-side factors impacting fuel economy. Conclusions Hydrostatic recuperation represents a feasible solution for railcars, provided that possible spatial and economic obstacles can be overcome. As the simulation results are promising, further hybrid configurations will be considered for simulation. A comprehensive comparison to models of hybrid diesel railcars using different energy storages is the next step.