New figures from the Central Statistics Office show a 20.6% jump in new car sales in August. This follows a 51% jump in July after the introduction of the new 132 number plate at the start of that month.
The CSO said that a total of 4,504 new private cars were licensed last month compared to 3,736 the same month last year.
Today's figures also show that a total of used or imported private cars licensed for the first time jumped by over 48% to 4,422 in August.
They also reveal that the number of new goods vehicles licensed in August rose by 12.1% to 1,018.
Of the 4,504 new cars licensed in August, 24.4% were petrol and 74.2% were diesel.
The most popular make of new car licensed last month was Volkswagen (564), followed by Toyota (465), Ford (412) and Hyundai (325).
Commenting on today's CSO figures, Merrion economist Alan McQuaid said that the new registration system introduced this year looks set to boost sales in the second half of 2013.
''But, overall, new car sales for the year as a whole are likely to be lower than in 2012, with a decrease of around 5% on the cards,'' he added.