Firefighters had to tackle flaming fuel on the A30 on Sunday after being called to a burning car.
Crews from Truro were called to the raod between Boxheater junction and Carland Cross just before 10pm.
A spokesman said that the fire spread from the car to a "running fuel fire", and that the crew used two sets of breathing apparatus, one foam jet and two hosereels to extinguish the flames.
The cause of the fire was accidental.
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