These descriptions are close to exactly what I believe happened.
1. Owner + passenger go for test drive.
2. Owner hammers it at the end of the street to show acceleration.
3. At curve, car understeers and starts to drift right.
4. Driver possibly tweaks wheel to the right to avoid parked car (see post
#194)
5. On the grass, car's left wheels hit and run over large manhole at high speed (see post
#194). This may result in enough damage to the left side of the car to jam left-hand side doors.
6. Car crashes into trees, but impact is not enough to intrude much into passenger compartment (see post
#86). Airbags likely deployed and protected the driver and passenger.
7. Fire begins, prompting driver and passenger to exit.
8. Due to 12V failure due to crash or physical jam condition, doors cannot be opened with electronic push buttons. Driver is owner, possibly knows and/or tries mechanical door release but with door jammed, can't get out. Passenger likely has no idea about mechanical door release.
9. Driver climbs to back to try to exit rear doors, again cannot open door either due to 12V failure, jam, or unable to access (or no knowledge of) rear door mechanical releases.
10. Driver and passenger become unconscious due to smoke inhalation.
11. Fire consumes car. Removes evidence of airbag deployment and seat belt use, leading to incorrect conclusions by first responders.
Autopilot / FSD / TACC had nothing to do with this accident.
One more tidbit: Why does driver's rear tire not burn? Because it's the closest part of the car to the firefighters (nearest to the hydrant, the fire truck's parking place, and the access path that the firefighters would have taken), thus it's getting the most water sprayed on it or near it. This is also further evidence that the fire developed a lot slower than the media is reporting. The tire survived from time of impact to the time that the firefighters got water onto the car, that's several minutes.
Yes, this is all pure speculation on my part. But I believe it to be the most likely and plausible scenario that fits the facts.