The incident was reported on A2032 Littlehampton Road around 1:20am on Tuesday (December 17).
According to an eye-witness, a horn reportedly sounded before vehicle ‘exploded’. Photos taken at the scene show large flames, with heavy smoke in the area.
A spokesperson for West Sussex Fire & Rescue Service said: "At 1.22am we responded to a vehicle fire at Littlehampton Road, Durrington.
"Joint Fire Control sent one fire engines from Worthing to the scene.
"Upon arrival firefighters wearing breathing apparatus quickly got to work to extinguish the fire, which was of accidental ignition, using hose reels and thermal imaging cameras.
"One casualty was treated for minor smoke inhalation.
"South East Coast Ambulance Service (SECAmb) and Sussex Police were also in attendance."
SECAmb said an ambulance crew ‘came across the incident’ and ‘stopped to assist’.
A spokesperson added: “One patient was assessed and discharged from the scene.”
The westbound carriageway was cleared and reopened by 7am.

1. Worthing car fire
A car burst into flames on a road in Worthing in the early hours of the morning. The incident was reported on A2032 Littlehampton Road around 1:20am on Tuesday (December 17). Photo: Sussex News and Pictures

2. Worthing car fire
A car burst into flames on a road in Worthing in the early hours of the morning. The incident was reported on A2032 Littlehampton Road around 1:20am on Tuesday (December 17). Photo: Sussex News and Pictures

3. Worthing car fire
A car burst into flames on a road in Worthing in the early hours of the morning. The incident was reported on A2032 Littlehampton Road around 1:20am on Tuesday (December 17). Photo: Sussex News and Pictures