The Renault had been covered in paper flowers for the Battle and some had since been removed.
On Monday night it was parked on Colin and Mary Paver’s driveway in Epinelle Road, St Sampson’s, alongside the couple’s silver Skoda.
Mr Paver had headed to bed by 11pm, while Mrs Paver was watching television, when a neighbour came to tell them there was a fire.
‘I was shocked,’ said Mr Paver.
‘The flames were 10ft high. The tyres burst with a bang. The petrol tank blew and threw flames across the driveway like a flame thrower.’
The fire spread to the couple’s Skoda, which was too close to the fire to be moved.
The emergency services had been called, but firefighters were tackling the fire at Church Road at the same time.
However help was at hand.
Guernsey Fire & Rescue station officer Dave Hockey was driving the fire duty officer car to help co-ordinate the Church Road fire, when the call about the car fire came in.
He diverted to Epinelle Road, where a police officer was on scene. The pair were faced with the Renault fully engulfed in flames, while the Skoda was starting to smoke.
With no fire appliance in sight, he managed to get a garden hose and they were able to get the fire under control.
‘I went there to do an assessment and realised I could get on with it,’ he said.
Extra fire cover was called in and the crew of a water carrier was able to ensure the fire was fully out.
Mr Paver said they did not know what caused the fire in the car, which has not been moved since it returned from the North Show.
Police are investigating.