During a joint operation with the Sheriff's Office of Victoria and the Victorian Taxi Directorate, police performed 1000 preliminary breath tests, checked the roadworthiness of cars and taxis and used a high-tech scanning device to find drivers with outstanding fines and unregistered cars.

Acting Sergeant John Auchterlonie, of Oakleigh police, said an automated numberplate recognition device checked whether cars were registered and whether the listed driver had any outstanding fines.

Acting Sergeant Auchterlonie said about 4500 cars were scanned.

He said police issued 43 penalty notices, mainly for cars that were unregistered.

Four people were caught driving while disqualified, one driver was found to be over the legal blood-alcohol limit and nine cars were found unroadworthy.

Acting Sergeant Auchterlonie said it was disappointing that so many drivers flouted basic road rules and regulations.

"People need to realise that by not paying their registration they are not covered by any [Transport Accident Commission] insurance and insurance companies won't cover them for any motor vehicle accidents."

As part of the operation, the Victorian Taxi Directorate checked 49 taxis. It issued notices for four defective cars and eight with minor defects.