Police said the car was travelling south along the roadway before it crossed over double lines, clipped the truck and rolled. 

The male driver of the car survived and was conveyed to hospital in an ambulance helicopter.

But police said his female passenger died at the scene.

The truck driver was not injured.

Police have launched an investigation into the incident and called on anyone who may have been along the road near the You Yangs to come forward.

The fatality brings this year's road toll to 140.