Figures from the Central Statistics Office today show the number of new cars licensed in January fell by 4.8% compared to the same time last year.
The CSO says that a total of 10,469 new cars were licensed last month, down 527 from the 10,996 licensed the same time last year.
Today's figures are in marked contrast to figures from the Society of the Irish Motor Industry released earlier this month. The SIMI figures showed a 5% increase in January sales and said the increase was due to buyers' interest in the Government's scrappage scheme.
The SIMI figures are based on car registrations, while the CSO numbers are based on when the car is taxed. The SIMI said that due to bad weather in early January, most registrations took place late in the month, and - due to a gap between registration and taxation - this could have affected the figures.
It says it is still expecting new car sales of around 70,000 this year, up from 54,400 last year, helped by the scrappage scheme.
Today's CSO figures show that the number of new goods vehicles licensed in January 2010 rose by 4.1% to 1,016 from 976 the same time last year.
The CSO says that out of the 10,469 new cars sold last month, 35.2% were petrol and 60.6% were diesel.
The most popular brand of new car sold last month was Ford, which sold 1,731 models. It was followed by Toyota (1,610), Renault (1,074) and Volkswagen (1,066).