By James Rodgers
BBC News, Moscow
Drivers in Moscow are currently facing what the city authorities have declared "clean car month".
Wash Me: dirvers disagree on what should be classed as "dirty"
Many cars have been out of use over the harsh winter. But motorists who fail to ensure that their vehicles are free of dirt and grime are liable to be fined.
Needless to say, it is not popular with car owners who are are questioning the legality of the move.
They say it is just an opportunity for unscrupulous traffic policemen to fine drivers.
In winter, some Russians simply keep their cars off the streets. Blizzards make driving difficult.
Temperatures of -20C and below can cause cars to seize up completely. In spring, vehicles reappear on the roads as if from hibernation.
Degrees of dirt
Motorists argue that Russian law is only broken if the number plates are obscured by grime.
Many traffic policemen, car owners say, take advantage of drivers' ignorance of the law to demand fines for offences real or imagined, or bribes to look the other way.
Motoring programmes on Moscow radio stations have been informing drivers of their rights, and encouraging them to challenge officers who stop them.
The website of the newspaper Izvestiya asked its readers for their views, and 46% agreed a car was dirty if the number plate was not visible.
Twenty three per cent said it was if the car had "wash me" written on it, 22% if the make or the colour of the car could not be determined. A stubborn 9% maintained that a car was dirty only if the actual driver was invisible.