Project Titan, the Apple self-driving car campaign, has hit a major speed bump when it terminated dozens of workers, while failing to show proof of its progress.

The retrenchment of employees was reported by NYTimes after talking to three insiders who are not allowed to speak about the development in public.

Apple has poured in more resources into its self-driving car, and even appointed Bob Mansfield to head the project, but there's scarcely any news on how it's going and when it's coming out. This is hardly new, of course, since the company is notorious for keeping its products a secret.

Tim Cook, Apple CEO, apparently referenced to the self-driving car during a shareholders meeting earlier this year when he told the audience, "Do you remember when you were a kid, and Christmas Eve, it was so exciting, you weren't sure what was going to be downstairs? Well, it's going to be Christmas Eve for a while."

Apple is not the only company struggling with the self-driving car concept. Google also has had its roadblocks, despite almost unlimited resources and early headstart. To be fair, the search giant has a more ambitious plan as it wants full autonomy in transportation industry, said the report.

In contrast, Tesla has announced a new update to its own autopilot cars with its software version 8, which makes the onboard radar as the primary control sensor which will improve maneuverability, braking and environment mapping.

To date, the news about the retrenchment of employees in self-driving car project has yet to be confirmed by Apple.