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The transmission is one of the key subsystems that influence the fuel consumption of the modern passenger cars. This is induced by the transmission efficiency and the engine operating points that result from engine-transmission-vehicle combination on a given test cycle. This paper aims to investigate the global performances of a modern transmission in different test cycles including the newly introduced WLTC (Worldwide Harmonized Light Vehicles Test Cycle) considering a variable powertrain thermal regime.

The study is done using a complex model developed in a performant simulation environment. In order to compare the performances in different test cycles, one needs to determine specific parameters such as: vehicle speed fluctuation (VSF), overall transmission efficiency, fuel consumption ratio (FCR). The simulation results are compared against those obtained at constant thermal regime, the test cycles are compared using a relative parameter (FCR) and the correlation between FCR and VSF is analyzed.