Car sales in June were 15% lower than the same month last year.
New car registrations have increased for 17 months in a row, until the drop in June.
However, sales for the year to date are 25% ahead of 2014, according to Motorcheck.ie, and projections for the second half of the year remain positive.
The market is expected to pick up this month, as the 152 registrations become available.