Revenue has caught over 1,100 drivers using 'green diesel' in road vehicles since the beginning of 2019.
Fines of over €1 million have been handed out over the past three years.
Tax is paid at a much cheaper rate for marked gas oil, or green diesel.
It can be used for farming purposes, but not on road vehicles, and is dyed green to deter misuse of it.
Revenue samples fuel in vehicles at checkpoints.
Nearly 28,000 tests took place in 2018 and marked gas oil was detected 835 times.
This rose to 867 in 2019 when over 6,000 more tests were carried out.
There has been a sharp reduction in 'diesel-dipping' during the Covid-19 pandemic.
Of the 7,000 Revenue inspections carried out in the first ten months of this year, there were 244 misuse detections.
Since 2018, 385 people have been prosecuted for using green diesel in road vehicles.
