New figures from the Society of the Irish Motor Industry show that new car registrations for May slowed down by 10.3% to 5,303 from 5,914 the same month last year.
SIMI said that registrations so far this year are up 3.2% to 63,045 compared to 61,091 the same time last year.
But they are still 20.5% behind pre-Covid levels of 79,350 new car registrations.
SIMI said that used car imports for last month slumped by 35.2% on May 2021, while year to date imports are down 34.4% on 2021 levels.
Meanwhile, 744 new electric vehicles were registered last month compared to 534 in May 2021.
So far this year 8,261 new electric cars have been registered compared to 3,940 on the same time 2021, SIMI said.
Today's figures also reveal that light commercials vehicles are down 37.4% compared to May last year and so far this year are down 22.5%.
HGV (Heavy Goods Vehicle) registrations are up 9.5% on May 2021, while year to date HGV registrations are down 12.4%.
SIMI said that electric vehicle, plug-in hybrids and hybrids continue to increase their market share, with a combined market share now of 43.14%.
It also noted that petrol continues to remain dominant with a 27.96% market share, while diesel accounts for 26.46%, Hybrid 22.87%, Electric 13.1% and Plug-in Electric Hybrid 7.17%.
Brian Cooke, Director General SIMI, said that new vehicle registrations continue to remain challenging, with a slowdown during the month of May, reflecting the international supply chain issues.
"New car registrations year to date are over 20% behind pre-Covid levels, while sales of commercial vehicles, both Light and Heavy Good Vehicles (HGVs), also remain subdued," Mr Cooke said.
"Despite the decline in May new car registrations, the sale of electric cars continues to grow, with EV sales for the first five months of the year over double that of the same period last year," he added.
SIMI said the five top selling car brands so far this year are Toyota, Hyundai, Volkswagen, Kia and Skoda.
The top car model registered so far this year are the Hyundai Tucson, the Toyota Corolla, the Toyota C-HR, the Toyota RAV 4 and the Toyota Yaris.
Meanwhile, the top selling car in May was the Toyota Corolla.