Hampshire Constabulary were called at 1:30pm on Thursday (April 23) after a 30-year-old man leaving a shop on Clarendon Road was approached by a man wielding a knife.
The suspect told the driver to get in the BMW and begin to drive, entering the vehicle alongside the driver.
Just before reaching the junction with Clarence Road, the suspect demanded the keys to the car – but the driver managed to stop and flee the vehicle, running along Clarendon Road.
The suspect was seen to run into alleyway in Malvern Road.
The victim was uninjured and recovered his car.
Hampshire Constabulary have released an image of a man they would like to speak to in regards to the incident.
A spokeswoman from the police said: ‘(We) also want to speak to an elderly couple who were seen in the area, as well as anyone who has any dash cam footage from the area at that time, or who saw the incident unfold.’
Anyone with information about the incident is asked to call 101, quoting 44200143191.