Glen Eira Bayside Crime Investigation Unit detectives are investigating a fraud in Brighton on 9 August.
Investigators have been told a man posing as a car washer attended at the victims address in Wells Street and after obtaining the keys, stole the victims black Holden Commodore sedan, registered 1MX4CM about 3.30pm.
The victim had earlier sold her car on a car sales website and after the sale, had received an email purporting to be from the website telling her she had won a free car wash.
The man is described as being European in appearance, 177cm, black hair, medium build, wearing a blue shirt, yellow hi-vis top and a baseball cap.
Investigators are urging anyone with information to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au