FONTANA, Calif. - It's the ultimate robot reality show: 43 contestants battling for a spot in a government-sponsored desert race intended to speed development of unmanned military combat vehicles.
The reward? A $2 million cash prize.

The autonomous robotic vehicles were scheduled to compete Wednesday in the first of a series of qualifying rounds at the California Speedway. Half will advance to the Oct. 8 starting line of the so-called Grand Challenge.

The grueling, weeklong semifinals are designed to test the vehicles' ability to cover roughly two miles of the track without a human driver or remote control.

Participants ranging from souped-up SUVs to military behemoths will be graded on how well they can self-drive on rough road, make sharp turns and avoid obstacles - hay bales, trash cans, wrecked cars - while relying on GPS navigation and sensors, radar, lasers and cameras that feed information to computers.

The robots also have to heed speed limits in certain zones and pass through a 100-foot-long tunnel designed to temporarily knock out their GPS capabilities.

"It looks like a piece of cake," Sebastian Thrun, a computer science professor at Stanford University, said of the qualifying course that will challenge his team's entry, a converted Volkswagen Touareg dubbed Stanley.

The Grand Challenge is sponsored by the research arm of the Pentagon known as the Defense Advanced Research Projects Agency, which is spending $9 million on this year's event.

The competition is part of the Pentagon's efforts to have a third of the military's ground vehicles unmanned by 2015 to fulfill a congressional mandate.

This year's race will cover about 150 miles of desert and mountainous terrain looping to and from Primm, Nev.

The exact route, over desert roads and mountain trails, is kept secret until hours before the race.

The first vehicle to traverse the entire course in less than 10 hours wins. If no one finishes - a possible outcome - another competition could be held.

Last year's inaugural race in the Mojave Desert ended without a winner when all the entrants broke down before the finish line.