Police have been waiting to ask George Michael, who is in hospital following an accident, to find out how he catapulted from a car at 70mph.
Officers are piecing together what happened in the seconds before the singer crashed on to the M1.
Questions are being asked about whether the star, who has previously battled drugs and depression, fell from his Range Rover or may have jumped of his own accord, the Mirror reported.
The car company has refused to be drawn on how easy it was to "accidently" fall from its vehicle.
But respected Autocar Magazine columnist Colin Goodwin said it would be "very, very difficult" to do so.
He said that "it has a huge side impact bar running through the middle, and electronic motors and -equipment for the windows and locking system, which means it takes real effort to open it."
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After the singer was airlifted to hospital with a head injury last Thursday, police sources confirmed the accident was still unexplained and "far from cut and dried".
Investigators are concentrating on the testimony of two other men who were also in Michael's vehicle - the driver and a fellow passenger.