The purpose of this experimental study is to investigate the effects of the compressor performance improvement on the fuel economy in a automotive air conditioning system. The cooling performance tests for compressors are performed in the compressor calorimeter test stand, and then the fuel economy evaluation test in vehicle with the same compressors was done in the climate wind tunnel(CWT). During the fuel economy evaluation test, the compressor driving torque was measured by a torque sensor attached directly on the clutch of compressor. In the compressor calorimeter test of the performance improved compressor, cooling capacity is found to be increased about 2~3%, but COP was worsened about 2~3%. Meanwhile, in the vehicle test, performance improved compressors are found to improve the cooling capacity by 1.7~2.0%, but fuel economy was worsened about 1.0%.