With 2,123 units registered, the Fiesta has just pipped its sibling Focus, which has had 2,067 units registered in the new car sales sector.
VW's Golf is third with 1,880 and Nissan's Qashqai completes the top five at 1,803 units.
Overall car sales are up 38 percent at 42,795, according to Motorcheck.ie, whose figures are used in this story.
