Inter-vehicle distance is important to achieve safety driving support system. In this study, we discuss the accuracy improvement method for inter-vehicle distance estimation using GNSS. We propose Local-DGNSS scheme, which uses correction information provided from near a vehicle that has two receivers. Those relative positions of the two receivers are known. For more accurate correction, we also apply novel GNSS satellites selection to the proposed Local-DGNSS. We present the effectiveness of the proposed method through performance evaluation with real observed data.