Buyer power in public procurement: evidence from the diesel fuel market in Greece

Abstract This article investigates the causes of variations in diesel fuel procurement prices paid by different Contracting Authorities focusing on potential buyer power, which is defined as the ability to negotiate or secure favorable pricing terms. Based on a sample of 736 public contracts for the supply of diesel in Greece (2020–2022), the study proposes a Buying Power Index (BPI), which is calculated as the percentage discount from the prevailing market retail price, in order to quantify the purchasing power per case. Descriptive statistics and graphical analysis are used to summarize and visualize the discount trends and patterns, while regression techniques are applied to assess the impact of various factors on the discounts offered. The analysis reveals that the sector of activity, the applied deductions and the competitive procedures significantly influence the amount of discounts. In particular, in low-value contracts, it is observed that economic operators reduce discounts to compensate for losses from deductions, essentially shifting the financial burden back to the Contracting Authorities. This study provides correlational evidence contributing to a deeper understanding of how institutional and market factors shape public procurement outcomes. The findings provide valuable insights for policymakers seeking to design fairer and more efficient procurement systems.