Drivers in China's largest city, Shanghai - already cursing traffic jams and roads being ripped up in a building boom - face a new challenge.
The systems use satellites to track a vehicle's progress
GPS navigation systems designed to help people reach a destination are getting them lost instead - because some of them use counterfeit electronic maps.
The Shanghai Daily said drivers were tempted to buy the counterfeit maps because they were much cheaper.
Fake maps now far exceeded the number of legal ones, the paper reported.
The paper said that the Chinese Academy of Surveying and Mapping had granted eight companies across the country a certificate allowing them to produce electronic navigation maps.
The systems rely on satellites which accurately determine a vehicle's position and, using electronic maps, can show a driver which route to take.
A manager from one of the authorised firms told the paper: "Generally a GPS device costs about 10,000 yuan but a fake one equipped with a counterfeit electric map can be available for several thousand yuan or even less.
"Both its function and accuracy are doubtful," the manager said of the cheaper variety.