All it took was one letter to derail George Hotz's self-driving car promises.
In September 2016, Hotz took the stage at TechCrunch Disrupt, a competition in San Francisco for startups, and announced he was mere weeks from selling a device that could turn a regular car into a self-driving car.
He whipped out a device that looked like an original Nintendo DS gaming system and said the Comma One would be "harder to come by than a pair of Kanye West sneakers."
Six weeks and a lot of media attention later, Hotz announced that he was canceling the project after receiving a letter from NHTSA questioning the device's safety and efficacy and urging Hotz to delay releasing it until he could prove it would be safe.