A police patrol came across the blue Mercedes on fire in Blackheath, south-east London, at 2am.
The body was discovered after fire crews tackled the blazing vehicle.
A Scotland Yard spokesman said that officers believe they know the identity of the dead man but await formal identification.
Detective Chief Inspector Damian Allain said: “At this early stage we don’t believe that this was a random killing and are exploring the line of inquiry that this was a targeted attack against our victim.”
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