According to the Society of the Irish Motor Industry just over 4,000 new cars were registered in the Premier County between January and September 2016.
This compares with slightly less than 3,500 for the same period last year.
SIMI Director General Alan Nolan described the increase in T reg cars as particularly encouraging.
New car sales across the country to the end of September were 143,190 which is up 18.4% on the first nine months of 2015.
