Albert Ding & Matthew Robertson
Epoch Times 
June 14, 2011
For years now Chinese authorities have been installing spying devices on all dual-plate Chinese-Hong Kong vehicles, enabling a vast network of eavesdropping across the archipelago, according to a Hong Kong newspaper.
The report in Apple Daily states that the recording devices began being installed as “inspection and quarantine cards” in July 2007. They were installed without charge by the Shenzhen Inspection and Quarantine Bureau on thousands of vehicles.
Smugglers were the first to note something strange about the devices. A source told Apple Daily that after the cards were installed mainland authorities had no trouble picking off the cars carrying illicit goods.
“For every ten cars we ran we only had [smuggled goods] in three or four to reduce the risk, but the border agents caught all of them. The accuracy was unreal!” Apple Daily quoted the smuggler saying.