The engine indicated torque is not delivered entirely to the wheels, because it is lowered by losses, such as the pumping, mechanical friction and front auxiliary power consumption. The front auxiliary belt drive system is a big power consumer-fueling and operating the various accessory devices, such as air conditioning compressor, electric alternator, and power steering pump. The standard fuel economy test does not consider the auxiliary driving torque when it is activated during the actual driving condition and it is considered a five-cycle correction factor only. Therefore, research on improving the front end auxiliary drive (FEAD) system is still relevant in the immediate future, particularly regarding the air conditioning compressor and the electric alternator.An exertion to minimize the auxiliary loss is much smaller than the sustained effort required to reduce engine friction loss. The purpose of this paper is two-fold: first, to measure a quantitative accounting value of the FEAD system driving torque for evaluating the loss in accessories ; and second, to devise a useful measure for reducing friction of the FEAD system using the assessment standard. In order to determine whether the proposed scheme is worth developing, this study investigated the fundamental features of the FEAD system. Many methods have been devised to minimize the driving torque in the 2.0 L diesel engine FEAD system. During the measurement, the accessory load controller and temperature control chamber were widely used for the actual driving environment. After modifications to the FEAD system, such as V- ribbed belts, layout, idler, tension and auxiliary, driving torque was dramatically reduced. Hence, it can be an important measure to improve vehicle fuel economy in the standard test modes, such as Federal Test Procedure (FTP), New European Driving Cycle (NEDC) and real driving emission (RDE) tests.