Fire erupted in Pitaya Pukaman's car just as it reached Ban Krot in Bang Pa-in district of Ayutthaya and it took firefighters about 30 minutes to put the blaze out.
The former embassador to countries like Chile and Bhutan said he was driving from his home in Nonthaburi province to Chiang Rai on a pleasure trip with his wife beside him. His friends in another car that was following called him on the phone, telling him to pull over as they had noticed smoke and sparks under his car.
The couple abandoned the car just before the blaze erupted and tried in vain to use a fire extinguisher to put it out. Rescue workers rushed to help them after the incident was reported to police and the fire was controlled before it burned into a CNG gas cylinder in the trunk.
Pol Lt Col Pitak Yingnueawong of Pang Pa-in police said the car was severely damaged by the fire. It could have been worse had the cylinder exploded.
Mr Pitaya said the fire could have been caused by a short circuit and the natural gas in the car.
Mr Pitaya was an executive member of the Pheu Thai Party and an assistant to the natural resources and environment minister in 2013.