Even though the company has never acknowledged its existence, Apple's self-driving car project is an open secret. The iPhone maker is said to have been working on the so-called "Project Titan" for at least the last two years, but a report from the New York Times claims that the electric vehicle initiative has run into trouble.

Citing three people briefed on the move who were not allowed to speak about it publicly, Apple has decided to "reboot" the project. While the reasons behind the decision are unknown, it has resulted in dozens of employees being laid off and the closure of several parts of the project.

The rethink is reportedly connected to the appointment of Apple veteran Bob Mansfield as head of Titan back in July. The executive changed the team's focus from building an electric/autonomous car to developing the underlying technology for self-driving vehicles.

A number of other companies are way ahead of Apple when it comes to autonomous technology; Uber is bringing its self-driving taxis to the streets of Pittsburgh this week, while NuTonomy's driverless cabs are already on the roads of Singapore.

Should Apple ever release a completely autonomous car, by the time it arrives - thought to be around 2021 - it will be entering a market packed with similar vehicles from the likes of Google, Tesla, and numerous automobile manufacturers. The Times added that people working on Titan "struggled to explain what Apple could bring to a self-driving car that other companies could not."

The future of Apple's car initiative may be unclear, but it still has "a number of fully autonomous vehicles in the middle of testing, using limited operating routes in a closed environment."