Groundwater contamination from vehicular oil spills due to stormwater runoff is a major concern in highly impervious areas. This paper examines the potential of Enhanced Porosity Concrete (EPC) in retaining spilled oil in its pore structure. In this study EPC mixtures with porosities varying between 13 and 35% were examined. Known quantities of oil were introduced in different EPC specimens and rain events of different magnitudes were simulated. Oil recovered in the water that drained through the sample was quantified using a partition gravimetric method. The influence of (i) material properties of EPC such as porosity and pore sizes, and (ii) varying environmental conditions such as rainfall intensities and rates of oil and water addition on the quantities of oil retained by the system was quantified. It has been found that there is a certain optimal range of porosity in which the oil retention by the system is maximum. These experimental studies provide an understanding of the influence of pore structure features that contribute to retention of seeped oil in EPC.