The accident took place at Ganeshghat, about 60 kms from here, when they were proceeding to Pune from Indore.
The car was rammed in the rear by the truck following which both vehicles caught fire, killing all the four occupants of the smaller vehicle on the spot, they said.
The victims, including a woman, have been identified as Dilip, Mayank, Samay and Rashmi, police said, adding that a case has been registered.