The number of new cars licensed for the first time fell by over 17% in August, while the number of imported cars jumped 34% as buyers continued to cross the border to take advantage of the weak sterling.
New figures from the Central Statistics Office show a total of 8,105 new private cars were licensed for the first time last month compared to the same time last year, down 17.1%.
A total of 8,220 used or imported private cars were licensed, up 34% on the same time last year.
Today's CSO figures show that in the first eight months of 2017, a total of 116,767 new private cars were licensed, down 10% compared with the same time last year.
But the number of imported cars licensed increased by 42.8% in the eight months to August compared to the same time in 2016.
August also saw a 13.1% decrease in the number of new goods vehicles licensed, bringing the total to 2,080.
The CSO figures capture the point at which a car is first issued with a valid motor tax disc, however they are broadly in line with figures from the Society of the Irish Motor Industry, which refer to the point at which cars get their licence plate.
Last week's SIMI figures showed that new cars registrations so far this year are down 10% on the same time last year.
Today's CSO figures also reveal that Volkswagen was the most popular make of new private cars licensed in August, followed by Ford, Toyota, Skoda and Nissan.
Together these five makes represent 43.3% of all new private cars licensed.
In the first eight months of this year, almost 65% of new private cars licensed were diesel.