Single cylinder SI engine tests were conducted with low octane primary reference fuel (PRF) blends and methanol. The investigated parameters were equivalence ratio, and PRF octane number ranging from 100 to 53 blended with weight percentages of methanol to 75 percent. In order to evaluate the performance of these different fuels, knock intensity, efficiency and emissions were considered.The results indicate that even a 53 octane number PRF blended with methanol displays some performance advantages over pure isooctane. This is best detected from the observed efficiency increase for all of the PRF blends except the 91 octane PRF blend. The improved efficiency is also higher than that of pure methanol.