The concept of the self-driving car has been on the horizon for decades, and could soon become a reality. Following this concept, Alex Davies reveals that Defense Advanced Research Projects Agency (DARPA) set out to create a land-based equivalent to the drone, issuing a series of three "Grand Challenges" that attracted a wide range of visionaries. Many of the students and amateurs who responded later went to work for Google, Uber, and automakers, but as this history clarifies, the challenges of driving a car without human assistance were more formidable than anticipated.