Well, I have some sources for that information: http://www.newyorker.com/reporting/2013/11/25/131125fa_fact_bilger?currentPage=all http://www.newyorker.com/rep

Well, I have some sources for that information: http://www.newyorker.com/reporting/2013/11/25/131125fa_fact_bilger?currentPage=all http://www.newyorker.com/reporting/2013/11/25/131125fa_fact_... It's a long article, but search for "rain." Here's the most important quote for our purposes: Left to its own devices, Thrun says, it could go only about fifty thousand miles on freeways without a major mistake. Google calls this the dog-food stage: not quite fit for human consumption. “The risk is too high,” Thrun says. “You would never accept it.” The car has trouble in the rain, for instance, when its lasers bounce off shiny surfaces. (The first drops call forth a small icon of a cloud onscreen and a voice warning that auto-drive will soon disengage.) It can’t tell wet concrete from dry or fresh asphalt from firm. It can’t hear a traffic cop’s whistle or follow hand signals.