Police believe two car jackings a week apart could be linked.
A 27-year-old woman was walking towards her car in Buckhurst Hill Tube station car park at around 6.45pm on Friday when a man approached her with a screwdriver.
He ordered her to hand over her keys and purse, before driving away in her Mercedes and crashing into another car parked outside the Railway Tavern pub.
He then abandoned the vehicle and ran to another waiting car nearby.
It is believed he was picked up by several other men, who were in a small vehicle with ‘L’ plates which had been parked opposite the Mercedes.
The suspect is described as white, aged between 18 and 20, 5ft 7ins, of slim build, with short dark hair.
He is said to have been wearing a red top, light blue jeans and white trainers.
Detectives also want to trace the driver of a silver Smart car which was seen to leave the car park at the time of the theft.
Police are linking the incident to an attempted car robbery in the same location on January 10, involving a red BMW.
A 39-year-old woman was approached by two men at around 6.00pm who demanded her car keys, but she refused and a struggle ensued.
One of the men eventually took the keys and started the vehicle, before a member of the public pulling into the car park at the time saw what was happening and got into the passenger side of the vehicle in an attempt to stop it.
Both suspects fled and got into a dark blue car waiting nearby and took the woman’s iPhone.
The two men were described as Asian, in their late teens or early 20s and were wearing jeans and hoodies.
Speaking about the latest incident, investigating officer DC Stephen Baker said: "This was a terrifying ordeal for the victim and she genuinely believed this man would have caused her serious harm unless she handed over her property.
"Although the car has been recovered the thief managed to make off with the victim's handbag which contained her purse and luckily no cash.”
Drivers are urged to be on their guard when using the car park and to report any suspicious activity.