A hidden Tesla feature nicknamed 'Elon mode' is under scrutiny from regulators after a hacker discovered a way to get rid of a prompt to drivers to keep their hands on the wheel

• Auto regulators ordered Tesla to hand over data about a hidden Autopilot mode that lets drivers stay hands-free.
• It reportedly removes a prompt telling drivers to put their hands on the wheel, and was discovered by a software hacker.

The National Highway Traffic Safety Administration says Tesla has an Autopilot mode that lets drivers go hands-free for an extended period of time, and has ordered the company to hand over data about it, Bloomberg first reported.

The NHTSA's letter was sent to Tesla last month as part of an investigation into its vehicles crashing into emergency vehicles. The letter was posted to the agency's website on Tuesday.

It raised concerns about an Autopilot configuration that would let drivers "operate their vehicles for extended periods without Autopilot prompting the driver to apply torque to the steering wheel."

Typically, if a driver using Tesla's Autopilot or Full Self-Driving feature takes their hands off the wheel, a visual symbol blinks on the car's touch screen. If they still don't place their hands on the steering wheel, it escalates to a beeping noise, and if there's still no action then the ability to use Autopilot can be disabled.

The Verge reported that this could be disabled back in June, after a software hacker said they'd discovered the secret configuration and dubbed it "Elon mode."

The NHTSA's letter said it was concerned drivers may attempt to activate this potentially dangerous mode since it was reported. Tesla has not publicly confirmed whether or not it exists.

"The resulting relaxation of controls designed to ensure that the driver remain engaged in the dynamic driving task could lead to greater driver inattention and failure of the driver to properly supervise Autopilot," the agency's chief counsel said in the letter.

Tesla's manual says that, when using Autopilot, drivers should "keep your hands on the steering wheel at all times."

Elon Musk said last December that a software update would let some Tesla drivers disable the "nag," but that hasn't yet been implemented.

The NHTSA confirmed on August 25 that Tesla had filed a confidential response to its letter.

Earlier this month, Musk livestreamed himself driving a Tesla in Palo Alto, California while using a phone – a violation of Tesla's own rules and California state law.

Palo Alto police told The Verge that Musk would escape a fine for using his phone while driving because no officer had witnessed it in person.

Tesla did not immediately respond to Insider's request for comment.