Waymo recently put its new self-driving Pacifica minivans to a different kind of test. Arizona’s Chandler Police and Fire departments lent their emergency vehicles to help Waymo’s cars gain some key knowledge. Dealing with emergency vehicles, like police cars and ambulances, is a key challenge for autonomous cars. Waymo was able to gather data as emergency cars passed, tailed and drove near its vans. The vans are now much better able to detect police, fire and medical emergency vehicles – potentially before humans could do the same.