Wakefield District CID would like to speak to anyone who has seen or has information about the incident which took place between just after 3am on Jubilee Way or Wakefield Road on Saturday, December 15.
Officers would particularly like to speak with two women who were already in the vehicle when victim got in, and who got out at Featherstone.
The incident occurred after the 19-year-old victim had earlier flagged down what he believed was a taxi between Farmer Copley’s and the Kings Croft Hotel on Wakefield Road.
The car was heading to Sharlston after the the two women were dropped off, when the victim was sick in the taxi.
The driver is then said to have stopped on Wakefield Road near to where he had picked up the victim, pulled the male out of his car and assaulted him.
He then took cash from the victim and drove off.
The victim was left with an injury to his head as a result of the incident but did not need hospital treatment.
Detective Inspector Sam Freeman of Wakefield CID, said: “We are investigating this assault and robbery and would like to speak with anyone who has information about what took place.
“We would in particular like to speak to the women who were already in the vehicle, described as a light coloured car, to see if they can offer further details about the driver or the car.
“Anyone who has information or who can assist the investigation is asked to contact Wakefield District CID on 101 referencing police crime number 13180627392.”