A father-of-three from Rothwell died after dousing himself in petrol and setting it alight while driving on a busy motorway to a custody hearing, an inquest has heard.
Foyzul Islam, 43, died instantly when his Mercedes burst into flames at 60mph along the M11 near Cambridge.
The vehicle was seen swerving from side to side before coming to a halt as it exploded.
The melted remains of a petrol container were discovered in the rear of the car, capable of holding about two gallons, and a second similar container in debris in the front, alongside a plastic cigarette lighter.
An inquest into Mr Islam’s death on Thursday heard he was filmed on CCTV buying petrol minutes before the incident, when he had filled up the car and a can.
He then continued on his journey to the the Royal Courts of Justice in London on January 13.
Traces of petrol were later found on Mr Islam’s clothing, indicating it had been spilled or put there deliberately.
Driver Jill Threlfall told the inquest in Huntingdon that it appeared he was fiddling with something in the footwell or on the passenger seat.
She said: “All of a sudden I saw the old silver Mercedes blow up.
“I would say the explosion was from the rear of the vehicle and came from behind the driver’s seat because I saw a silhouette of the driver.”
Ms Threlfall said the car stopped almost immediately after the explosion so she pulled over and called the fire service.
The fire was so intense the tops of the vehicle’s doors had bowed and it needed four times the usual amount of water to extinguish it.
The inquest heard that shortly before his death, Mr Islam, of Marlow Close, had been taken to hospital after overdosing on medication, but claimed it was accidental.
Det Insp Simon Harding from Cambridgeshire Police investigated the death.
He concluded that no-one else had been involved in the incident and that the cause of the fire had been deliberate ignition.
Station commander Geoff Quince from Cambridgeshire Fire and Rescue investigated the cause of the fire and said a sniffer dog trained in detecting hydrocarbons was used during its investigation.
Coroner David Morris recorded that Mr Islam took his own life while suffering from depression.