Tesla Motors CEO Elon Musk delivers Model X electric sports-utility vehicles during a presentation in Fremont, California September 29, 2015.  REUTERS/Stephen Lam Thomson ReutersTesla Motors CEO Elon Musk

Tesla Motors CEO Elon Musk thinks it's pretty obvious that Apple is working on its own electric car, and that the iPhone maker would be a really good auto manufacturer, too, he said during an interview with BBC.

"It’s quite hard to do, but I think companies like Apple will probably make a compelling electric car. It seems like the obvious thing to do," Musk said during the interview. "It's pretty hard to hide something if you hire over 1,000 engineers to do it."

When pressed if he thinks Apple's serious about building its own car, Musk said, "Yeah, I do. This is an open secret."

Apple has been rumored to be working on an electric, and perhaps a self-driving, vehicle over the past year. It's been reported that Apple hired thousands of engineers to work on a secretive car project, internally called Project Titan.

In fact, just last week, Apple was found to have bought a bunch of web addresses related to cars, including apple.car and apple.auto.

This isn't the first time Musk hinted at a possible competition with Apple in the electric car space. In October, he jokingly said that Apple only hires people fired by Tesla, acknowledging the iPhone giant may indeed be preparing to get in to the auto space.

"We always jokingly call Apple the 'Tesla Graveyard.' If you don't make it at Tesla, you go work at Apple. I'm not kidding," he said.

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