New figures show that the number of new cars licensed in January was up 12.6% on the same month last year.
The Central Statistics Office said the total of 32,961 new cars was the highest number for any month on record.
The increase was much bigger than the 4% rise reported by the industry body SIMI. The SIMI figures cover cars registered for Vehicle Registration Tax, while the CSO figures calculate the number of new cars taxed for the first time.
A spokesman for SIMI said the figures are usually different at the start of the year because of the time lag between the two taxes.
The second-hand rise was a more modest 1.1%, while new goods vehicles fell 10.8%.
There had been expectations among some that car sales would slow ahead of new rules on VRT and motor tax due to come into force in July, as it was thought some people may wait to avail of savings from lower-emission cars.
