Elon Musk claims data logs show Tesla in which 59-year-old and 69-year-old died was NOT on autopilot - yet cops say neither was in driver's seat as Twitter pics reveal how easy it is to trick car into thinking someone is at the wheel

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Tesla is facing serious questions over its safety systems after two men died in a fiery crash in Texas on Saturday after taking the car for a 'spin' on autopilot and plowing into a tree just a few hundred yards down a quiet cul-de-sac.

The men haven't been named but one of their relatives told Click 2 Houston anonymously that the owner of the Tesla Model S drove it out of his driveway then jumped out of the driver's seat and into the backseat - where he was found dead - after engaging autopilot. The other man was in the passenger seat.  

Within a few hundred yards of the driveway, they smashed into a tree on a bend that the car's steering systems failed to anticipate. 

Tesla founder Elon Musk meanwhile claimed that the car couldn't have been on autopilot, according to 'data logs.' He also said the car's owner had not purchased the 'FSD' option, which stands for 'full self-driving.'

It's not clear how Musk's claims stack up against those of the local police, whose investigators said they were '99.9 percent sure' there was no one behind the wheel of the car. Three other people have died in Tesla autopilot-related incidents.

The two men on Sunday were driving along Hammock Dunes Place in Spring, Texas, a street that is just 1,000ft long in a gated community where the average house price on the street is more than $2million. 

Tesla lovers are baffled by the crash because to engage autopilot, the $80,000 car must be able to identify clear road markings (which this street does not have). The men were also driving at night, at 11.25pm. 

After they plowed into a tree just a few hundred yards from the house they left, the vehicle caught fire and for four hours, firefighters battled the blaze while the victims' relatives watched on in horror.

They had to call the carmaker and ask how to stop the battery from reigniting. In the end, they used 32,000 gallons of water but the two men were incinerated. 

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This was the aftermath of the Tesla crash on Saturday night. It took four hours for firefighters to put out the blaze while the victims' relatives watched on helplessly

They were driving along Hammock Dunes Place in Spring, Texas, a street that is just 1,000ft long in a gated community where the average house price on the street is more than $2million. Tesla lovers are baffled by the crash because to engage autopilot, the $80,000 car must be able to identify clear road markings (which this street does not have). The men were also driving at night, at 11.25pm.

The car did not turn along with the bend in the road and instead plowed straight into trees then caught fire 

Police say that the battery in the vehicle kept catching fire which made it impossible for them to put it out for hours

Now, there are serious questions over how the men were able to get as far as they did when no one was in the driver's seat. 

Tesla insists that to engage autopilot, a person must have their hands on the steering wheel at all times, ready to take over if the automated systems fail. 

If no weight is detected on the steering wheel, the car sends the driver an alert reminding them of the rule, but it doesn't necessarily bring it to a stop - at least not right away. 

In some videos posted by car enthusiasts, it takes two minutes for it to even detect that no one has their hands on the wheel.  

In one from 2019, it took the two minutes to detect no one was behind the wheel. The car then sends the driver an on-screen prompt, then it starts beeping loudly before finally slowing down. 

In the 2019 video, it took 40 seconds from the first prompt for the car to stop completely. 

It's unclear how fast the men in the crash were driving but detectives say it was at considerable speed. 

Tesla will stop driving on autopilot if it cannot detect a person's hands on the wheel. To get around it, people have been doing this - putting an item on the wheel or lodging it there - to trick it 

Others have balanced water bottles on the steering wheels or attached them in drink holders to trick the car (left) or attached weighted bangles to it (right)

Other drivers balanced water bottles on the steering wheel to make the car think they were still engaged with it

This is what the driver is told via the screen in the car if, after 30 seconds or so, no hands are detected on the wheel. The car makes a loud beeping noise then it starts to slow down and comes to a stop but it can take half-a-minute to do so

Both the NTSB (National transport Safety Board) and the NHTSA (National Highway Traffic Safety Administration) are investigating the crash. 

Elon Musk hasn't commented on the latest crash. He tweeted this before the crash on Saturday

The NHTSA said in a statement: 'We are actively engaged with local law enforcement and Tesla to learn more about the details of the crash and will take appropriate steps when we have more information.  

The National Transportation Safety Board (NTSB) said on Twitter it had dispatched two investigators to the scene, who 'will focus on the vehicle's operation and the post-crash fire. 

Tesla's share price dropped by 3.4 percent on Monday 

'NTSB investigators will arrive in the area later this afternoon.'

Tesla has not commented. 

On its website, it is vague about what exactly happens if no one is at the wheel when autopilot is engaged.

'Before enabling Autopilot, the driver first needs to agree to “keep your hands on the steering wheel at all times” and to always “maintain control and responsibility for your vehicle.” 

'Subsequently, every time the driver engages Autopilot, they are shown a visual reminder to “keep your hands on the wheel,"' it says.

Saturday's crash happened hours after Elon Musk tweeted that the autopilot function was becoming 'ten times safer'.

On YouTube, car enthusiasts have been sharing videos for years about how to trick the steering systems with oranges, weighted bangles or just by simply giving the wheel a nudge. 

Some have wedged water bottles in the steering wheel to trick it too.  After the crash, Tesla's stock plummeted by 3.32 percent on Monday.  

Hours before Saturday's crash, Musk tweeted: 'Tesla with Autopilot engaged now approaching 10 times lower chance of accident than average vehicle.'