The no-car days, introduced on Oct 11 to reduce gridlock and pollution, have apparently left so many drivers scratching their heads that one Beijing newspaper runs front-page notices each day to remind drivers which weekday they aren't allowed to drive.
But the rules are simple enough. If the last number of your license plate is a 1 or a 6, you cannot drive on Mondays. If the number ends in a 2 or a 7, you cannot drive on Tuesdays, and so on through Friday. Weekends are exempt.
"Starting from Monday, some cars previously banned on that day will now be allowed on the roads," the China Daily said, failing to add much light on the matter.
"They will not be allowed on Tuesdays. Cars banned on other days of the week will also move back a day."
Beijing adopted the restrictions after the success of a broader ban during the Olympics in August that kept half of all cars off the road each day, reducing transport times and pollution.
"Changing the days, I fear, will lead to confusion," Canadian media consultant Robert Miller was quoted as saying. "People are likely to forget when they can and cannot drive."
(Reporting by Beijing newsroom; Editing by Nick Macfie and Sanjeev Miglani)