There are estimated 137,000 untaxed vehicles on Irish roads, according to MyVehicle.ie.
The car history check service published statistics on second-hand cars today, which also stated that around 8,400 cars have been written-off so far this year.
Car clocking, write-offs and false NCT certificates are some of the issues that show up during a MyVehicle.ie history check.
Speaking about the statistics, Justin Kavanagh, managing director of MyVehicle.ie said: "Safe driving is essential to improve our road safety in Ireland; however, the vehicles themselves must also be in safe operating condition.
"Purchasing a second-hand car can be an overwhelming experience. MyVehicle.ie offers drivers the reassurance that the car they are purchasing is of a safe standard with a traceable history.
He added: "During Irish Road Safety Week, I would urge all drivers who are considering purchasing a second-hand car to make an informed decision.
"A vehicle history check costs just 18 euro – a fraction of the maintenance and repair costs which could be incurred from buying a faulty second-hand car."