Engineers in automotive industrie are trying to provide the same level of quality and durability with more economic materials. In this study, the use of an alternative material was investigated for a crown wheel and pinion design used in differential gear systems of light commercial vehicles. Changing gear set material manufactured with both current and proposed material was a cost reduction step by keeping same manufacturing processes. Hardenability characteristics of the gear sets were compared. Accelerated fatigue tests were performed in rig test set up with dynamometer and gear sets manufactured with proposed materials were assembled to light commercial vehicles and durability tests were performed on real road conditions. It was seen that hardenability characteristics of current and proposed materials are so close. Gear sets manufactured with proposed material performed durability test were completed successfully. However, the differentials assembled to durability test vehicles were tear down and it was realised pinion head bearing and pinion tail bearing inner ring contact areas were damaged. Proposed materials usage will be approved after design modification and repeated durability tests. Additionally it is determined that the accelerated fatigue test results in dynamometer test rigs does not overlap with the road test results.