"I said, 'Look man, we should partner,' " Kalanick stated in the book. "Elon spent the rest of the call convincing me that it's too far out, and it's not realistic, that I should just stick to what we do best and be focused, or I'm going to fuck it all up. That's when I knew Tesla was competing."

Kalanick wasn't aware that Tesla was already working on autonomous vehicle tech, even though it had unveiled its "Autopilot" driving assistant hardware. Shortly afterwards, Musk detailed a master plan for self-driving Tesla cars, including an autonomous ride-hailing service that would directly compete with Uber. Tesla has done perhaps the most impressive fully autonomous demo yet, steering a car from a customer's house to Tesla offices and parking without any human intervention.

Uber, meanwhile, has been mired in problems. It was sued by Google's Waymo self-driving division for intellectual property theft and now risks a criminal prosecution. On top of that, it recently demoted self-driving lead Anthony Levandowski, who was subsequently barred by a judge from working on any projects involving crucial LIDAR tech.