A man has allegedly fired a shot at another motorist during a road rage incident in Melbourne's west on Christmas Day.

Police say there was a minor collision between two cars at Kings Park last Wednesday afternoon, after which one of the vehicles left the scene.

The other driver, aged 66, then followed the man, and the two had a verbal argument as they drove along Taylors Road.

Police say a shot was fired through the 66-year-old's front windscreen, narrowly missing him and lodging in the rear seat.

Police say the man who fired the gun was a caucasian male aged in his late teens.

AAP