"It's not the everyday, one-off sellers who cause the difficulties. It's the illegal traders who pass themselves off as private sellers and buyers have little or no legal recourse when dealing with these characters."
Mr Stronach said in many cases, the details they provided were incorrect and the purchaser was then unable to locate them after the money has changed hands.
The rules on car sales are strict and anyone selling more than six vehicles a year must be a registered motor vehicle trader (RMVT).
"But some of those operating from roadside venues simply pass off the cars they are selling as belonging to a 'family member'. Many of these cars will have been recently added to the Vehicle Register, which can sometimes be a clue," he said.
While there are quick and easy ways to make thorough vehicle background checks - MotorWeb is one example - buyers continued to bypass the proper checks and end up dealing with illegal traders.
They end up making a deal but with none of the legal benefits of dealing with a proper RMVT.
Mr Stronach said more roadside selling venues have sprung up around the country in recent years, and Wanganui, like most towns and cities, has at least one spot where roadside sales take place.
"While a small number of local authorities have banned them, primarily because of the traffic and safety hazards they create, most have been allowed to trade unimpeded."
Meanwhile, the Wanganui District Council is reviewing its bylaws but it is not known what changes could be made.
The current bylaw says no one could "cause or permit or allow" any vehicle they owned or controlled to remain parked in or on any road or public place for the purpose of hire or sale or for the purpose of repair.
But at the moment this bylaw is only enforced following a complaint, or if the car is causing a potential traffic hazard.
The council uses signs or no parking lines to prevent cars with 'for sale' signs being parked on public land (usually on green spaces) if there was potential for these to become a traffic hazard.
Wanganui District councillor Ray Stevens said the council preferred to adopt a "softly, softly" approach to anyone breaking the bylaw.
"We don't have the staff to have them out checking every street in the city on a daily basis to see if someone is flouting the bylaw," Mr Stevens.
He said the current bylaw meant that a public complaint would be acted on and the vehicle's owner given a warning and told to remove the vehicle.
"If they don't, then the vehicle will be ticketed or possibly towed away. But there's been nothing like that happen to my knowledge."
However he warned that anyone continually flouting the bylaw would be prosecuted through the courts.
"People need to understand that council will act if we get a complaint," he said.
Mr Stevens said the parking zone in London St in front of the Splash Centre, was a popular spot but because it is part of the state highway network it is NZ Transport Agency's responsibility. "But if the numbers of vehicles parked there gets any bigger it will be a problem and we'll be talking with NZTA.
"Owners need to remember roadside car parks are not the place for car sales," he said.
Melanie Heron, the council's customer services group manager, said the council had received four complaints about roadside car sales in the past 12 months.
Ms Heron said the current bylaw was due for a review and council would undertake public consultation before implementing anything new.
She said the bylaw was drafted following concerns from the community about cars being parked on roadside reserves.
"The concerns were about safety, such as drivers stopping to look at parked cars, or where multiple vehicles with 'for sale' signs were likely to cause traffic hazards," she said.
Ms Heron said the majority of cars parked on roadside reserves, providing they are registered and legally parked, do not cause safety issues, so this aspect of the bylaw will need to be reviewed.
