Firefighters and Guernsey Police were called to the incident in the car park near the Auberge at Jerbourg on Monday afternoon at around 3.30pm.
An electrical fault is believed to be behind the accident.
An insurance assessor, who did not wish to be named, was examining the damage to the now unrecognisable green Chrysler yesterday morning.
'I've heard that there was a family in the car and that after they saw smoke billowing out of the bonnet, quickly unbuckled their seatbelts and escaped,' he said.
He added that once a car catches fire, it can be completely ablaze within 10 minutes or less.
'It's a good thing the family acted so quickly. With these kinds of fires, there is not much you can do to prevent it.
'Older cars are more at risk but it is relatively unpredictable.'