Michigan boasts three core strengths when it comes to its ambitions to market itself as a rigorous autonomous-vehicle proving ground. First, a grimy, gray malaise blankets the state for two-thirds of the year and remains capable of producing frost and snow any time between October and early June, giving developers a true chance to test in all-weather conditions. Second, roads in the state have been torn asunder by both weather and lack of government interest in infrastructure improvements, creating potholes the size of moon craters that challenge any vehicle, autonomous or not. And third, the state has some of the most permissive laws in the country when it comes to testing.
That?s an appealing trifecta for a company like Waymo, which said today that it will expand its testing to Michigan, chiefly to take advantage of the state?s lousy conditions. ?Having weathered 14 winters in Michigan, I can tell you firsthand that snow there comes in many different forms: light fall, dense flakes, powdery dust, and even slanted sleet,? Waymo chief executive officer John Krafcik wrote in a post announcing the expansion. ?For human drivers, the mix of winter conditions can affect how well you can see, and the way your vehicle handles the road. The same is true for self-driving cars.?

This isn?t Waymo?s first attempt at winter testing. Engineers have been testing the performance of sensors and the vehicle itself in cold-weather conditions since 2012, when the company was still known as...