Woman carjacked in her BMW

A 23-year-old woman was in her blue BMW convertible in Bankstown when she was carjacked.

A woman has been carjacked after being asked for a cigarette lighter in Sydney's southwest.

The 23-year-old was in her blue BMW convertible in Percy Street, Bankstown at 12.30am (AEST) on Sunday.

A man approached the stationary car and asked the woman for a cigarette lighter before grabbing her and dragging her out of the driver's seat.

He then drove off.

Investigators are looking for a man of Caucasian appearance aged in his 30s.

The car is estimated to be worth $70,000 and has the Victorian registration VMS-069.