Many road users driving older cars
Motorists are driving older vehicles as the number of cars over four years old on Irish roads has increased.
However, the total number of licensed vehicles on Irish roads has increased above 2.5 million for the first time.
Figures released by the Department of Transport reveal that more than 1.9 million of these are passenger cars but only one-third of those are taxed on their CO2 rating.
Cars registered after 2008 are liable for a motor tax payment based on CO2 emissions instead of engine size.
Four out of five cars on Irish roads are more than four years old, while 72pc are more than six years old.
This represents an increase of 5pc and 15pc respectively on the same figures for 2010.
The number of driving licences held in Ireland has also grown.
At present there are 2.71 million licenced drivers, and increase of 62,000 compared to 2009.
However, the number of drivers holding a provisional licence has decreased.
More than 91pc of Irish drivers hold a full licence, this figure had previously stood at 89pc in 2009.