Vendors play a key role in their company's success, so having a vendor's performance evaluation system in order to identify strengths, areas of improvement and profitability in any company is essential. In this paper, first data envelopment analysis (DEA) which is a technique to evaluate the performance of decision-making units (DMUs) is studied. Then the efficiency scores of 66 automotive vendors based on the DEA (CCR) are calculated using Lingo software. Then, based on the efficiency scores of each vendor, improvement plan with the help of the dual DEA model is presented to increase efficiency scores of inefficient vendors. Finally, it will be clear that each inefficient vendor for improving the inefficiency should focus on which of the factors.