Transport Infrastructure Ireland says a small number of motorists are "needlessly ending up in Court"
65 vehicles were seized last year for failure to pay the M50 toll, according to Transport Infrastructure Ireland (TII).
The 2016 seizures represent more than a third of the 170 vehicles seized to date.
In one case, a 'serial offender' was prosecuted and had to pay more than €16,000 after more than 1,200 trips on the road.
That individual's vehicle was also seized on foot of a civil judgement.
A spokesperson for the TII says the overall compliance rate on the toll road has 'marginally improved' in recent years to 97%.
The spokesperson explained: "There still remains a very small minority of motorists who use the toll road on a regular basis - in some cases three to four times a day - without paying.
'These people are needlessly ending up in Court and putting themselves at risk of incurring a criminal conviction, or having the debt registered against them as well as having their vehicle seized by the Sheriff."
Figures from the first quarter of 2017 showed an average of around 138,000 trips on the M50 every day.
The current tolls range from €2.10 for a car with a ‘tag account’ to €6.30 for unregistered heavy vehicles, with a barrier free system in place since 2008.