But according to car history check specialists Motorcheck.ie, the industry 'remains buoyant' and a 120,000 sales outlook for the full year is 'positive'.
The company also notes a 'booming' used car market, and with more cars in total on the road the service and maintenance sectors of the car trade are showing more 'positive trends.
In total, 90,893 cars were registered in the first six months of 2017.
Volkswagen registered the most, followed by Toyota, Hyundai, Ford and Nissan.
The top five models were Hyundai's Tucson, Nissan's Qashqai, Volkswagen's Golf, Skoda's Octavia and Ford's Focus.
Electric and hybrid vehicles now account for 3.7pc of the market.
Commercial vehicles registrations are also down, by 14pc to 18,889 units compared to the first half of 2016. The top selling commercial vehicles were the Ford Transit, VW Caddy, Renault Trafic, Ford Transit-Connect and Peugeot Partner.
