Car sales for September were 10% down on the figures for the same month last year, new statistics from the SIMI show.
2,487 new cars were sold last month compared to 2,767 in September 2011.
New car sales in the third quarter were down 1% on the figures for Q3 2011.
So far this year, 76,630 new cars were sold, down 12% on this time last year.
The top selling car makes in September were Volkswagen, Ford and Toyota.
The top selling models were the BMW 3 series, the Ford Focus and the Skoda Octavia.
