THE number of cars seized for non-payment of M50 toll fees in the first half of this year is more than four times the numbers taken last year.
During the first six months of this year, a judgement was approved for the sheriff to seize 17 vehicles, a significant increase from four in the 12 months previous.
Including VAT, the National Roads Authority (NRA) collected €4m in penalties for not paying the toll on the barrier-free motorway.
This figure accounted for just over 6pc of the total income (€68m) collected in the first half of the year from tolls, penalties and tag fees, according to the NRA.
Sean O'Neill of the NRA said despite the higher number of vehicle seizures this year, they are seeing an improvement in the compliance rate.
"One of the main reasons the figure for car seizures is so high is due to a delayed process in getting a judgement approved," he said. "In general, we are seeing a 96pc compliance rate which is considered very good within Europe."
The remaining 4pc of passages are made up of domestic vehicles and foreign vehicles, which have travelled through the M50 toll on multiple occasions.
Around 50 different countries have been identified as the origin of registration for foreign vehicles, and they have been pursued further by the NRA's foreign enforcement service provider EPC plc, a UK-based firm.
Since the introduction of the eFlow toll system in 2008, more than 37,000 people have had proceedings against them, and so far in 2014 the biggest fine paid by an individual was €8,000.
Mr O'Neill said that of the 4pc who choose not to pay the toll, only 2pc of cases end up being brought through the court system.
The remainder are sorted through a deal outside of court, when motorists realise the judgement may not end up in their favour.
"We have had cases where people have decided to settle on the steps of the court because they realise it's for their own benefit not to go in front of a judge," Mr O'Neill said.