An unknown man approached a silver Mazda CX5 in a primary school carpark on Flinders Avenue in Lara, around 16km north of Geelong, around 7.15am, police said.
The man threatened the driver, a 56-year-old woman, before pushing her out and stealing the car.
The woman was not injured.
Police are still looking for the male offender and the car.
An investigation remains ongoing.
Anyone with information is urged to contact police or CrimeStoppers on 1800 333 000.