The Casuarina-laden lorry was proceeding from Chidambaram to Coimbatore and the car was going to Kurinjipadi from Tiruchirapalli when the mishap occurred.
Another member of the family escaped by breaking open the window of the car, they said, adding, he has been hospitalised with severe burn injuries.
The lorry's driver was unharmed as he jumped out the vehicle before it caught fire.
The fire service personnel rushed to the spot and doused the flames within three hours, police said.