The number of miles is not what matters, but the number of trips in which a human driver can be reliably replaced by a robot. It doesn't matter how far the vehi

The number of miles is not what matters, but the number of trips in which a human driver can be reliably replaced by a robot. It doesn't matter how far the vehicle can go; what we care about is the degree of confidence we can have that the vehicle will reach its destination without incident. Designing for the unexpected edge cases is harder than designing for the normal cases. In accordance with Cargill's ninety-ninety rule, we can expect that the "fine tuning" you mention will be turn out to be a very big job. As an extreme demonstration, consider the fact that you could rack up a million "autonomous" miles in a matter of months, using vehicles capable of nothing more than "lane keeping assist" and "adaptive cruise control" - just set 'em loose on a NASCAR loop and run them around in circles until this artificial example's point has been proven.