A pair of sunglasses left in a car in bright sunlight set the vehicle alight.
The blaze destroyed the car parked in Nuthall, Nottinghamshire.
The fire was put out by fire fighters.
The Nottinghamshire Fire and Rescue said in a tweet:
“The sun has been strong but beware this can cause fire.
“Earlier we attended a fire caused by sunglasses left on the dashboard.
“Make sure you keep reflective objects out of direct sunlight.”
People who saw the photos on social media thanked the service for alerting them to the unknown danger.
One wrote: “Good information, looks nasty.
“Well done on giving out a warning and attending the fire.”
Another added: “Never knew that! Thanks.”
