Statistically, self-driving cars are about to kill someone. What happens next?

As autonomous vehicles rack up more and more miles on our roads, the odds of a fatal accident are shortening by the day. How will we react?

One hundred million. That's the number of miles, on average, that it takes a human driver to kill someone in the United States. It's also the number of miles Tesla's semi-autonomous 'Autopilot' feature had racked up by May this year. Assuming Autopilot is rolled out to Tesla's mass-market Model 3 in 2017, that number will rapidly climb into the billions. Mercedes are deploying similar systems in their new E-class, while Google's fully driverless cars have racked up another 1.6 million miles and counting .

As the miles grow, the odds shrink. At some point, a car driving autonomously or semi-autonomously will cause a fatal accident. If their performance is remotely comparable to a human's, that moment could come within the next 18-24 months. If so, by the law of averages it will probably involve a Tesla Model 3. Self-driving cars may be about to have their Driscoll moment.