Nationwide efforts to clamp down dodgy car dealers' online presence are paying dividends with four dealers caught in the Bay of Plenty in the last five years.

Figures released by the Ministry of Business, Innovation and Employment show between two cases more than $8000 in fines was dished out during the prosecution process in the Bay.

Four car dealers have caught in the Bay of Plenty in the last five years, according to the Ministry of Business, Innovation and Employment.

Under the Motor Vehicle Sales Act 2003 individuals can legally sell six vehicles in a 12-month period, without being registered as a motor vehicle trader.

Last November, Rotorua man Dick Dekin Tamai was convicted and fined $6430 for being an unregistered motor vehicle trader while two Tauranga motor vehicle dealers have been investigated in the last year.

Neither investigation resulted in prosecution – one trader receiving a warning letter and the other leaving the country.

Prior to this there has been the one conviction in the last five years with a Tauranga trader fined $1760 in December 2009.

The Bay figures coincide with the registry successfully prosecuting four people nationwide in March and April.

A 52-year-old man was convicted and fined $5400 in the North Shore District Court on March 7 for selling 10 vehicles without being registered as a motor vehicle trader.

Six days later, a 21-year-old man was found guilty of the same offence and fined the same amount at Auckland District Court for selling 12 motor vehicles.

On March 21, a 32-year-old man was found guilty at Gisborne District Court for selling 13 vehicles – receiving 80 hours community work.

On April 2, a 24-year-old man was convicted and fined $8,000 at Auckland District Court for selling 10 vehicles.

MBIE Registry and Integrity and Enforcement manager Karla Flood says compliance is the first objective, but the recent prosecutions are a reminder to the motor vehicle trade that enforcement action will be taken for those that don't abide by the rules.

'Buying a car is a significant purchase for people and it is vital that consumers have confidence in the industry,” says Karla.

'Unregistered motor vehicle traders are not subject to the checks that apply to those who are registered and consumers may have less protection when something goes wrong.”

The number of unregistered motor vehicle traders is on the rise, largely due to a change in trader behaviour towards online markets.

The Registrar of Motor Vehicle Traders works with TradeMe, New Zealand Customs and Land Transport New Zealand, to help identify unregistered traders.

Karla says the registrar's aim is to assist the traders to register so they are compliant with the legislation and only if this does not succeed does enforcement action take place.

Unregistered motor vehicle traders are not subject to the checks that apply to those who are registered and consumers may have less protection when something goes wrong.

Under the Motor Vehicle Sales Act 2003 those found to be carrying on a business of motor vehicle trading without being registered are liable to a fine not exceeding $50,000 for individuals and $200,000 for a company.

Since July 2012, the Registrar has investigated 422 unregistered motor vehicle traders.

Of those, 339 investigations have been finalised, 74 remain under investigation with the view of achieving compliance and nine cases are currently before the courts.

Since August 2013, there has been an increase of 379 new registered motor vehicle traders and the Registrar has obtained convictions for 17 unregistered vehicle traders.