New car sales were down 8% in February according to figures from the Society of the Irish Motor Industry, putting sales for the year so far down 15% in total.
That follows an 8.6% fall in sales in February 2012 when compared to the previous year and is more than 52% below 2008's February sales figures.
SIMI reported a rise in activity in the used car market, however, with sales in Light Commercial Vehicles also up last month.
This year saw the introduction of a new registration plate system, which distinguishes cars sold in the first half of the year from those sold from July onwards.
The motor industry had lobbied for the change in the hope that it would lessen the tendency of most customers to buy new cars at the start of the year.
SIMI’s Deputy Director General, Brian Cooke, said the industry was not anticipating a boost in sales due to the new system, but people now understood that it was a permanent change and not just for 2013.
"We still however expect the new registration plate to take some time to take hold, and hopefully it will continue to create interest as more and more of the new plates are seen on the roads,” he said.
“Clearly sales in March will be closely watched as the first quarter will be crucial as to how the year pans out."
Meanwhile the emissions-based tax system has continued to influence purchases, with 94% of cars sold in January and February 2013 falling into the two lowest emissions-based tax categories.
Nearly three-quarters of cars sold were diesel, with Nissan’s Qashqai and Volkswagen’s Golf being the most popular models so far.