An Invercargill man has been fined $7500 for selling cars as an unlicensed dealer.
And the Ministry of Business Innovation and Employment says the problem is swelling rapidly.
Keith Warren McLeod (56) appeared in the Dunedin District Court this week facing a charge under the Motor Vehicle Sales Act, which carries a maximum penalty of $50,000.
Under the legislation anyone can sell up to six vehicles a year without censure but more requires a person to be licensed.
Between January 2017 and January this year, McLeod sold 15 vehicles.
MBIE registrar of motor vehicle traders and manager of trading standards Stephen O'Brien said McLeod's conviction was one of 18 such convictions in the 2017-18 year.
"The number of unregistered and prosecuted traders is increasing, largely due to the growing online motor vehicle market,'' Mr O'Brien said.
McLeod was given three warning letters before he was finally prosecuted, the court heard.
It was a measure frequently used by the ministry.
Mr O'Brien said 834 letters were sent to unlicensed sellers in the past year.
Counsel Andy Belcher said his client had done his best to comply with the requirements by completing an online form and lodging a payment.
There were further steps before he could be licensed but "he felt at that point he had done all that was required''.
Ministry prosecutor Catherine Ure confirmed McLeod had begun the registration process but had not made any financial contribution.
In any case, the defendant's actions had come long after the unlawful activity, she told the court.
McLeod claimed he had sold the vehicles because they were part of a business fleet surplus to requirements and costs had to be met.
Judge John Macdonald said that did not mitigate the offending - the man knew that he was breaking the law and continued to do so.
"It seems to me this type of offending is increasingly becoming prevalent and perhaps problematic,'' he said.
Mr O'Brien said compliance with the licensing regime was important to give consumers protection.
"The Act states traders must display a consumer information notice, keep a record of the contract for sale and prohibit tampering with the odometers of a motor vehicle,'' he said.
McLeod was fined $7500 and ordered to pay $130 court costs and a solicitor's fee of $500.
