Powertrain configurations for hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV) are disclosed herein. One powertrain comprises: a prime mover; an electric motor-generator, said electric motor-generator mechanically coupled to said prime mover via a first clutch; an electric motor, said electric motor mechanically coupled to said electric motor-generator via a second clutch; a battery, said battery electrically coupled to said electric motor-generator and said electric motor, said battery capable of supplying electrical energy to said electric motor-generator and said electric motor; and a controller, said controller capable of supplying control signals to said prime mover, said first clutch, said electric motor-generator, said second clutch and said electric motor such that said controller is capable of dynamically affecting a plurality of operating modes; wherein further said plurality of operating modes comprises one of a group, said group comprising: all electric mode, series mode, series-parallel mode and parallel mode.