FORT WORTH — All Saints Episcopal Schools hand-built solar car had made it around the oval at Texas Motor Speedway and was second on a second loop around when a walkie-talkie crackled: Breakdown.The teens knew what to do. Driver Jack Walraven, 16, guided the car to a special lane, and teammates leaped out of nearby support cars to load the vehicle onto a trailer.It was only a drill, part of a two-day session at the speedway to help students practice skills they will use in the Solar Car Challenge cross-country race from Fort Worth to Los Angeles. The green flag will be waved at 9 a.m. Tuesday at the Northwest school district administration complex to start the competition.High school students from All Saints, Liberty Christian School in Argyle, Byron Nelson High School in Trophy Club and Ben Barber Career Tech Academy in Mansfield are among 14 teams from Texas and around the country in the race. Our car is perfectly functional, and we want it to be functional all the way to California, said Rob Drobnich, All Saints team captain. Just being here is really exciting. We want to beat or be on par with the other first-year teams.The Solar Car Challenge is intended to motivate students in science, engineering and alternative energy. Students designed, engineered and built their own solar-powered vehicles, a process that took a year or more, for the week-long journey. Breakdowns, weather conditions and road construction can limit the number of miles the team drives each day, and the winner is determined by the most miles accumulated during the trip. On Monday, the teams completed trial runs and road-worthiness tests at TMS, demonstrating to judges that the car can brake effectively and that teams are able to load the vehicle on a trailer if it breaks down.The vehicles, which carry liability insurance, will be tagged with Texas experimental vehicle license plates. The teams will travel in a four-vehicle caravan, with a lead car up front and two vehicles towing trailers and equipment following behind.Along the way, they will stop at various cities to meet with spectators, local media and young people, particularly those interested in science.Lehman Marks, president of the Solar Car Challenge Foundation, estimates the cars will pass about 10 million people along the route. Thats the function of our foundation, to motivate kids in science and engineering and alternative energy, Marks said. Towns empty out to come out and see the kids. Supporters can keep track of team exploits using various social media sites. The All Saints team plans a daily video blog on its website. And the Mansfield team has mounted a GPS tracking device on one of the support vehicles so folks can follow the journey.The Mansfield team is using a car that was originally built for a previous years contest but the teens completely reconstructed it. This years model, the Shine Runner II, is 300 pounds lighter, and while it has hit a top speed of 52 miles per hour, it cant sustain that pace, so the team hopes to travel at 30 to 35 mph during the race, said team adviser, Jackie Bishop, an instructor in the automotive technology program at the Ben Barber campus.Our goal is to make it to LA. We dont want any breakdowns. We want to get there with a working car at the end, said Chase Grigsby, 18, who graduated in May from Mansfield High School and plans to study mechanical engineering at the University of Texas at Arlington this fall.Teammate Taylor Davis added: We want to keep a consistent pace, but beyond that, we want to show that something powered by the sun is capable of amazing feats.