On the influence of the thermal demand on the overall efficiency of future drive train architectures for passenger cars

A new indicator for primary energy to wheel efficiency of different drive train architectures is derived, taking into account the thermal demand for cabin heating and all losses of the overall conversion chain. Battery electric vehicles are chosen as reference. The indicator is applied to an actual and a future scenario for three different car concepts: pure combustion engine, full hybrid and plug-in hybrid. In general, the actual scenario shows higher efficiency of all three car concepts compared to electric mobility. This is mainly due to the benefit of the combustion engine as a decentralised cogeneration unit. With an improved future electricity generation, the efficiency of electric drive is improved, resulting in the best efficiency of the plug-in hybrid. Furthermore, the time dependency of the power to heat ratio for different climatic conditions is analysed for the new European drive cycle and the influence on the new indicator is discussed.