The engine indicated torque is not entirely delivered to the wheels, because the torque is lowered by losses such as the pumping, mechanical friction and front auxiliary power consumption. The auxiliary belt drive system is big power consumer through the crankshaft even though it supports passenger comfort about cabin temperature, driving safety and electricity demands of vehicle. Auxiliaries such as air con compressor, alternator, water pump and hydraulic power steering pump have huge driving torque when it loaded on the actual driving condition, but it has been considered as 5 cycle correction factor only in the test standard. Therefore, research for improving the FEAD(Front End Auxiliary Drive) is still relevant in the immediate future especially air con compressor and alternator. The effort for reducing the auxiliary loss has been much smaller than that of engine friction loss comparatively. The purpose of this study is: first, to develop lower driving torque FEAD system which was driven by crankshaft pulley through v-ribbed belt using special test rig; second, to inspire lower driving torque auxiliaries for actual fuel saving using auxiliary torque assessment standard. To devise the ideas for less driving torque, this study investigated basics of FEAD system. The 2.0L diesel engine FEAD system was modified by devised technologies and measured using test rig which can simulate actual driving environment. After applying each modification on FEAD system such as V-Ribbed Belt, layout, idler, tension and irregularity of auxiliary, engine driving torque loss was improved dramatically and it can be important measures to reduce engine power loss on the FTP and NEDC modes also.