There is no evidence any product failure within Ford's control, caused the fire that burnt the Kuga Reshall Jimmy's body was found in, the Western Cape High Court heard on Wednesday.
There is also still no answer as to why he did not get out of the vehicle when the fire started.
"The cause of the fire is undetermined," said John Loud, the US-based expert hired by Ford to determine what happened to Jimmy's vehicle.
Jimmy was found dead in the car after the fire brigade put out the fire that engulfed his Ford Kuga in December, 2015.
After that, there were 52 incidents of fires in Ford Kuga vehicles, but nobody was injured. The fires led to a major recall by Ford of 4 670 vehicles in South Africa, in January 2017. This was to rectify an engine cooling deficiency.
At first there were theories about a mystery group of men driving away from the scene, supposed bullet casings found, an apparent casino binge, and the sound of a gunshot being heard.
The Jimmy family has the support of AfriForum's private prosecution wing led by advocate Gerrie Nel, a former National Prosecuting Authority prosecutor.
However, the inquest has now turned to the hard science of how a car works, and what could happen regarding a fire in the vehicle.
Loud wrapped up his evidence on Wednesday by submitting that the private forensic investigator, Daniel Joubert, hired by Jimmy's family, was wrong when he decided that the fire was started by a wiring fault near the body control module (BCM) of the vehicle.
He also accused Joubert of using "un-scientific" methods to come to his conclusion, and lambasted his methodology, saying a "solo" visit to the car at one occasion was also against fire investigation protocol.
Loud said he found numerous potential ignition sources in the vehicle, although he could not find evidence that they started the fire.
He named common items found in vehicles or handbags: hand sanitiser, a lighter, a cellphone charger, an electronic cigarette, a cellphone.
In Jimmy's vehicle a long braai lighter was also found, as was part of a faulty lithium ion battery.
He even named a tracking device, which was destroyed completely in the fire, as a potential source of ignition.
"A tracker is basically just a giant cellphone," he explained. He had heard of a case of battery problems with trackers in 2014.
There were also combustibles including paper, clothing and cologne in the vehicle that had not all been destroyed.
He found that the fire started in the front passenger side, but could not determine how.
Nevertheless, he concluded that the fire was not started by a wiring issue, nor a problem with the vehicle's BCM, as had been suggested.
He also demonstrated that the Kuga was designed in a way that allowed the driver the option of a manual door handle, in addition to the electronic locking system, and this handle opened a door even if the car had no power at all.
"Simply pulling on the handle would have opened the door," said Loud.
"Either an accelerant was used that caused the fire to grow so quickly, or Mr Jimmy was incapacitated at the time that the fire started, and grew."
Nel had hoped to cross examine Loud on Thursday but Loud is leaving South Africa in Thursday night. The inquest was postponed to Monday and Loud will be cross examined at a later date.