The number of new private cars licensed jumped by more than one third last month.
Figures from the Central Statistics Office (CSO) show 4,376 new cars were recorded in September, which is a jump of 34.4% compared to the same month last year.
In total, there were 86,894 new cars licensed in the year to the end of September 2014 - a rise of 30.5% compared to the same period in 2013.
The figure for 2014 in respect of used cars was 41,134, and this was up 9.9% from 2013.
But used cars licensed for the first time were down 7.6% to 4,376 in the year to the end of September.
The highest number of new cars licensed in September, by make, was Volkswagen (592) followed by Toyota (376), Ford (354) and Renault (323).
The number of new goods vehicles licensed in September was 1,485 - up 52.8%.