Vehicle dealerships are having a better year than in 2009, with sales up by 14%.
Commercial vehicles are particularly popular, with sales in May 37% higher than they were in the same month last year.
The Motor Industry Association says it's very happy with the figures, which are higher than the industry projected.
Just over 4600 new vehicles were registered last month - up 0.7% on April but a jump of 16% on May 2009.
Registrations of used cars - generally imported - totalled 7400 last month, which is nearly 5% more than April and 42% ahead of May last year.
Ford was the top-selling make in May, but for the year overall, the Toyota Corolla is the best-selling passenger car and the Toyota Hilux the most popular commercial vehicle.