New figures show that in the first half of 2015, 78,660 new private cars were licensed in Ireland.
That is a rise of 26.3% compared with the same period last year.
The number of used cars licensed fell by 10.8% compared with the same period last year.
In June, 3,924 new cars were licensed for the first time - an increase of 15.8% compared with June 2014.
While 3,765 used cars were licensed, representing a fall of 16.4% on the same month last year.
Who's buying what? | Source: CSO
The licensing figures also show that Volkswagen was the most popular make of new private cars licensed in the first half of 2015.
This was followed by Toyota, Ford, Nissan and Hyundai.
These five makes combined represent just over half of all new private cars licensed.
The total number of new vehicles licensed during June was 6,380 compared with 5,123 during the same month in 2014 - a 24.5% increase.
There was also a 68% increase in the number of new goods vehicles licensed last month.