A system and method for testing a specimen such as a vehicular power transmission (e.g., an automatic transmission) and analyzing an engine output characteristic of an engine connected to the power transmission in which at least a first revolutional speed on an input or output shaft of the power transmission and a first output torque of the power transmission are measured when the engine operating parameters indicate a predetermined value with the power transmission connected to the engine. A second revolutional speed on the input or output shaft of the power transmission and a second output torque of the power transmission are measured when a low inertia driving unit having the same characteristics as the engine is connected any driven with a power transmission under the same operating parameters described above. A first drive torque of the low inertia driving unit is then measured, a third revolutional speed on the input or output shaft of the power transmission and a third output torque of the power transmission are measured when a predetermined time has passed and when the same low inertia driving unit is connected and driven in the same way, and a second drive torque of the lower inertia driving unit is measured when difference values between the second and third revolutional speeds and second and third output torque fall within a predetermined range. The second drive torque is estimated as the output characteristic of the engine connected to the power transmission.