"Bot 3-2 has been given permission to commence operation," the announcer booms. "Victor Tango is on the move!" At just after 8 AM Pacific time, "Odin"—the modded SUV from Virginia Tech—purrs to life, passes in front of the bleachers to give spectators an eyeful, and disappears around the corner to a chorus of cheers. Odin's competitor number has a special significance; it honors the 32 students and staff killed in the recent Virginia Tech massacre. A few seconds later, the Stanford Racing Team's "Junior" gets the go-ahead. Junior lurches and pauses for a long moment just after exiting the blocks, but then regains its composure and follows Odin onto the course. The other nine vehicles follow, spaced a few minutes apart to decrease the odds of a collision.

A cortege of human-driven "traffic vehicles" escorts each autonomous entrant. The drivers are there to make sure the robotic vehicles don't "misbehave," as DARPA director Tony Tether puts it—but they could be putting their own lives on the line in the process. In earlier rounds of the competition, "on one merging turn, they had a bet on who was going to get hit first, and somebody won," Tether says. But not to worry, he quickly adds: "All these drivers are well-protected by cages built to NASCAR standards."—Elizabeth Svoboda

And then there were eleven. Yesterday, the Defense Advanced Research Projects Agency (DARPA) announced that it had narrowed the field for its Urban Grand Challenge to just under a dozen robotic vehicles. 35 teams were part of this week's qualifying rounds.

The finalists, which include a truck, a Prius and a sedan, will be competing this weekend for $3.5 million in prize money. To finish, each robot has to complete a 60 mile course in under six hours. And there's going to be live traffic—roughly 50 human-driven vehicles will be on the road. The robots will even have to deal with four-way-stops. Which would be amazing, since that's something most humans can't even figure out. Tomorrow, watch the race live here.—Gregory Mone