Musk has said that Tesla's new cars produced since October 2016 have the necessary hardware to eventually enable full autonomy.
GM's director of autonomous vehicle integration Scott Miller, though, said Tesla's promises about its autonomous technology are likely not accurate.
"I think he is full of crap," Miller reportedly told a group of journalists at a briefing in Detroit.
"To think you can see everything you need for a level five autonomous car [full self-driving] with cameras and radar, I don't know how you do that," he said.
Tesla did not immediately respond to a request for comment.
Tesla's new vehicles are equipped with multiple cameras, ultrasonic sensors, a long-range radar sensor, and other hardware to enable its semi-autonomous system, Autopilot. Musk has claimed that the new hardware suite, which was rolled out in new vehicles last October, will eventually enable full autonomy once the software is ready.
However, Tesla's vehicles do not have lidar sensors, which is a remote sensing technology that uses lasers to map out the world around it.
Most companies pursuing self-driving cars see lidar as a critical part of an autonomous system. Waymo, Ford, and GM all use lidar sensors to help enable their self-driving systems.
GM's recently rolled out its own semi-autonomous driving system called Super Cruise on new Cadillac CT6 vehicles. The system is widely seen as a challenger to Tesla's Autopilot, even though they work in different ways and Super Cruise has fewer features than Tesla's system.
GM's Super Cruise, unlike Tesla's Autopilot, uses a lidar sensors to help it better map out the world around it.
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