New car sales fell by almost 4.5% during 2018.
The Society of the Irish Motor Industry says the number of imported used cars topped 100,000 for the first time last year.
SIMI says Brexit and the weakness of Sterling caused the surge in imports, and the fall in new car sales.
The most top three new car models in 2018 were the Hyundai Tucson, the Nissan Qashqai and the Ford Focus.
Other noteworthy stats show that new electric car registrations for 2018 increased with 1,233 registered in comparison to 622 in 2017.
The diesel and petrol market share have moved closer, with diesel in 2018 accounting for 54% and petrol (including Petrol Hybrid) 44%.
Commenting on the figures SIMI Director General Designate, Brian Cooke said: “Despite the strong economic performance of Ireland last year, 2018 proved very challenging for new car sales...
"The Motor Industry is however as always forward-looking, and with the new 191 sales period now commencing, January and the first quarter will be the key focus for dealers...
"For consumers looking at the used car market, whether an Irish car or a used import, SIMI’s advice is to shop around and consider the real benefits of shopping in your local retailer, who not only provides value to the customer but also encourages economic activity locally.”