The man was driving along Sargentson Rd in Concongella, which is just north-east of Stawell, when he saw smoke rapidly rising from the footwell.

"I pulled over instantly and got out," he said.

"Then it (the car) went up in flames."

Stawell CFA officer-in-charge Mal Nicholson said firefighters were called to the scene at about 9.15am.

"The vehicle caught alight following a fuel leak from the LPG tank," he said.

"Fortunately, the driver and passenger are OK."

Mr Nicholson said four units - three from Stawell and one from Joel Joel - were called out to the scene.

Due to the highly flammable nature of LPG, onlookers were required to stand more than 200m away.

Other emergency services - Victoria police and Ambulance Victoria - were not required.

The matter is under investigation.