The battle between autonomous carmakers is heating up, with a GM exec making strong accusations about just how autonomous Tesla's Autopilot system really is.

Business Insider reports that GM Director of Autonomous Vehicle Integration Scott Miller said "I think (Elon Musk) is full of crap," when it comes to the level of autonomy that Telsa's current Autopilot hardware can deliver.

Tesla said late last year that all of their cars built since October 2016 would have all of the hardware necessary for "full self-driving capability." The features are not active because software and regulation need to catch up, but Tesla CEO Elon Musk has said that when the software and rules are ready, Tesla will be able to make those cars autonomous.

Miller disagrees. "To think you can see everything you need for a level five autonomous car with cameras and radar, I don't know how you do that," he said. Level five refers to a car that is capable of driving in all situations without intervention from a human driver.

Tesla's self-drive hardware lacks the lidar sensors used by other autonomous automakers, including GM, Ford, and Google's Waymo. Lidar works like radar, but it uses laser light instead of radio waves to detect distances and to let the car "see" the world around it. It gives a more detailed picture than radar can offer. The lidar sensors are the spinning cans you see on the roof of autonomous prototypes. GM, and their Cruise Automation subsidiary feel that lidar sensors are necessary for self-driving. That's why they announced yesterday that GM had purchased lidar sensor and tech company Strobe. GM's Super Cruise semi-autonomous feature, debuting on the Cadillac CT6, uses lidar sensors.