A powertrain includes a variable ratio transmission device having an input shaft coupled to an engine and an output shaft coupled to a driven unit, a three-way power split transmission device including three input/output couplings, a first of which is coupled to a flywheel and a second of which is coupled to an electrical machine. The third input/output coupling of the three way power split transmission device is mechanically coupled to the engine and to the input shaft of the variable ratio transmission device.