People selling cars privately are being asked to stay vigilant after an attempt to devalue a vehicle by putting oil in its water tank.
The incident, in St Edmund Road, Weeting, saw two men and two women - one of whom was pregnant - use the oil while the seller was distracted, in order to suggest the car was damaged.
They were challenged by the seller, and left the scene in a silver Audi A6.
The incident took place at around 12.30pm on December 7.
The four suspects are believed to be Asian.
Officers would like to hear from anyone who may have been approached in a similar way or have any information relating to the incident.
Witnesses are asked to contact Sgt Chris Archer at Norfolk Constabulary on 101 or Crimestoppers anonymously on 0800 555111 or through their Anonymous Online Form at www.crimestoppers-uk.org.
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