Police are searching for a man who allegedly drove off in a $120,000 Mercedes during a test drive in Melbourne's east.

Victoria Police said a 47-year-old man advertised the silver 2013 Mercedes C63 Coupe on the Carsales website.

Police said the victim got a call from a man identifying himself as "Billy", saying he was interested in the car.

The man met "Billy" and another man at Shepley Oval in Pultney Street Dandenong at 5:15pm on Friday and took him for a drive around the local area.

When he parked in the rear car park of a fast food outlet at 5:30pm, "Billy" asked if he could sit in the driver's seat, and while doing so sped off, police said.

Anyone who has seen the car, with licence plates ZPC 951, is urged to contact Victoria Police.