New figures show car registrations are up more than 30% - year on year - with more than 121,000 new cars registered to the end of September.
According to Motorcheck.ie show, this compares with only 93,000 units for the same period last year.
The top five manufacturers with the most new car registrations are Volkswagen, Toyota, Ford, Hyundai and Nissan.
Sales were also unaffected by the Volkswagen diesel emissions scandal with sales for the month up 23% on last September and with diesel cars accounting for 72% of sales in the month.
The figures show that sales of new diesel cars have increased by 26% this year whereas sales of new petrol cars have actually increased by over 40%.
Year-to-date sales of diesel cars account for 71% of all car sales.