Highway patrol officers in central and coastal Otago had noticed the trend was increasing, particularly in areas close to the Otago Central Rail Trail and other popular cycling routes.
It was also more of a problem during the summer holiday period and when cycling competitions were held.
Constable Howard Jackson, of Oamaru, said the covering up of registration plates and lights was punishable by a $100 fine and 25 demerit points.
Officers hoped the education programme would save motorists from being fined, and reduce the risk of traffic incidents, he said.
He had seen the entire back of vehicles covered by sheets in an effort to protect surface paint from being scratched by bicycles and carriers, which was a concern, Const Jackson said.
It was a safety issue, particularly at night, he said.
''It means other motorists cannot see tail-lights and number plates are also hidden. If it is dark then vehicles cannot be seen from behind,'' he said.
Those unable to position bicycles away from lights and registration plates could buy ''supplementary number plates'' for about $20, he said.
The plates were approved by the New Zealand Transport Agency under the Land Transport (Motor Vehicle Registration and Licensing) Regulations 2011.
Drivers could attach supplementary plates to bicycle racks, dog boxes and other objects which obscured permanent plates.
Various businesses throughout Otago had ''come on board'' with the highway patrol education campaign and stocked supplementary plates as well as information leaflets, Const Jackson said.
Pamphlets could also be obtained from police stations, he said.