The Defense Advanced Research Projects Agency (Darpa) has revealed the names of the 40 groups to compete in this year's Grand Challenge, a race for remote vehicles.

Over 100 groups applied to take part in the race and the teams announced today are not guaranteed a slot. They must first compete at an event at the California Speedway in Fontana on 27 September and the top 20 will race the full course.

"The high quality of vehicle performance that we witnessed during the site visits is truly impressive," said Darpa director Dr Anthony Tether.

"We are thrilled with the sheer excitement about developing autonomous ground vehicles that the Grand Challenge has sparked among people from all walks of life. It was difficult to winnow the field from the 118 great teams to only 40 and the competition was tough."

The cars will have to complete a 175-mile desert course with no human intervention within 10 hours. Darpa has put up $2m in prize money for the winning team.

The first competition, held last year, was a bit of an embarrassment for the agency. No car managed more than eight miles, and many failed to make it out of site of the start line.

The vehicles had particular problems recognising barbed wire and passing under bridges, and losing GPS signals.

"The odds are 20:1 against any starter, but we like those odds, and we like the payoff," said Dr William 'Red' Whittaker, whose Red Team made it the furthest last year. "The only sure way to lose is to not compete."

The project is being funded by Darpa with the ultimate goal of making one of three ground military forces automated by 2015.