The Toyota sedan was being driven in a westerly direction near the turnoff to Marrangaroo Fields when the engine began to falter and smoke erupted from the engine compartment when the driver moved to the roadside.

The car was totally engulfed in flames when fire brigades from Lithgow and Lithgow West arrived.

While one fire crew began extinguishing the car fire other brigade members were kept busy controlling a grass fire rapidly spreading from the car along the side of the highway and the adjacent railway corridor.

Paramedics treated one passenger at the scene for minor smoke inhalation.

Highway traffic was not seriously disrupted.