KINSTON - Lone Wolf, the robot sports car that is learning to drive itself, lost its cool Thursday under a blazing sky and the withering scrutiny of three Pentagon officials with matching stopwatches, walkie-talkies and red ball caps.

The blue robot Lotus roadster, sponsored by a Cary-based team of engineers and students, is one of 53 semifinalists in a Defense Department competition to help design vehicles that will drive themselves through future war zones.

The little car had no trouble at first. It showed off its knack for hitting the brakes, making a three-point turn and motoring around a 500-meter course on an abandoned runway at Kinston's Global TransPark airport.

But as temperatures climbed into the high 90s at midday, Lone Wolf lost its mojo. After steering adroitly around a minivan parked in its path, the car stopped cold -- seemingly flummoxed by an orange traffic cone.

It wasn't the radar, the lasers, the GPS gear or the video cameras that went bad. It was a 25-amp fuse in the air conditioner bolted to the roof, pumping cold air through four silver hoses into a trunk crammed with Mac Mini computers and a wireless network router.

"It is just brutally hot out there," explained Walt Sliva, a retired automotive engineering executive who lectures at N.C. State University, as the car cooled off in a shady garage. Sliva is a member of Insight Racing, a team of engineers and students who have taught Lone Wolf all it knows about driving.

The secret to Lone Wolf's street smarts is in software that makes sense of what the car "sees" via video, radar and laser sensors -- and tells the car where to go.

That's what the Defense Advanced Research Projects Agency wants: vehicles that will navigate war zones that aren't safe for drivers. A four-year competition will culminate Nov. 3 with the DARPA Urban Challenge, a 60-mile race through mock-urban traffic to be staged somewhere on the West Coast. The first three finishers will share $3.5 million in cash.

"This competition is another way to stimulate research," said Bill Coblenz, one of the three DARPA judges Wednesday.

With time running out, the Insight Racing team members plucked one of the silver cooling hoses out of the trunk and pushed it into a side window, held fast with duct tape, to cool the passenger cabin. Lone Wolf pulled up to a four-way stop again, waited for the second car to drive off, then drove off to a happy chorus of whoops and yelps.

There were four more variations of four-way stop etiquette, then it was over. The judges from Washington gave no hints about whether Lone Wolf would be among the 30 finalists to be named in August. Congress wants one-third of all U.S. battlefield vehicles to be able to operate without drivers by 2015.