The dynamic performances of the cooling circuit have a great impact on ICE efficiency and CO2 emissions. Engine thermal management is among the most promising technologies able to offer a sensible reduction in terms of engine fuel consumption and CO2 emission. These aspects are widely treated in literature and many technologies are already on the market or ready to be used. A reduced attention in literature, has been done on the pump performances during the real operating conditions. Homologation cycles try to reproduce these conditions. In light duty vehicles these cycles consist in accelerating and decelerating the engine following a specified velocity-time sequence. According to this procedure, the propulsion power requested by the vehicle is low, and the power absorbed by the auxiliaries became significant. The pump of the cooling fluid is the most important component among the auxiliaries. In this paper, the performance of a cooling pump has been studied according to its operating points when a homologation cycle is run: the variability of the engine RPM drives, in fact, the pump at different speeds whose values are in a fixed ratio with engine RPM. Being the hydraulic load of the circuit known, the pump produces a sequence of flow rates variable during time. A procedure to evaluate the variation of the pump speed during the homologation cycle has been developed. This time-pump speed variations have been used as set point in a dynamic pump test bench which reproduces closely the cooling circuit of the engine. Thanks to the wide applicability of the test bench, the limits of the usual centrifugal pumps have been discussed; the energy required to drive the pump has been measured and compared with that requested to drive the vehicle. Moreover, the coolant pump has been re-designed having as target the NEDC working points.