<p><em>This story is part of a </em><a href="http://news.nationalgeographic.com/news/energy" target="_blank"><em>special series</em></a><em> that explores energy issues. For more, visit <a href="http://www.greatenergychallenge.com/" target="_blank">The Great Energy Challenge</a></em>.</p><p>Students learn as much about teamwork as they do about engineering in the Shell Eco-marathon competition to design fuel efficient vehicles.</p><p>Teams from 30 universities and 18 high schools from the United States and Canada converged on Houston for Eco-marathon Americas competition on April 16 and 17. They brought 69 homemade vehicles to the U.S. oil industry capital for a weekend of slow-speed racing (averaging 15 mph), all to show it is possible to create cars that use less fuel.</p><p>(Related: "<a href="http://news.nationalgeographic.com/news/energy/2011/04/110418-shell-ecomarathon-houston-winners/">Canadian Students Win Shell Eco-marathon</a>")</p><p>Shante Stowell (left) and Semira Kern of Granite Falls (Washington) High School share a cheer in their pit area in the George R. Brown Convention Center while teammate Pooja Sethi smiles. Granite Falls, the first all-girls team to enter Shell's 26-year-old Eco-marathon program, won the diesel division prize last year and had high hopes for their lime green vehicle, the Iron Maiden, this year.</p><p>(Related: "<a href="http://news.nationalgeographic.com/news/energy/2011/04/110406-shell-eco-marathon-all-girls-team/">All-Girls Team Seeks Record in High-Mileage Marathon</a>" and see "<a href="http://news.nationalgeographic.com/news/energy/2011/04/pictures/110407-granite-falls-shell-eco-marathon/">Pictures: High School ‘ShopGirls' Design for the Prize</a>.")</p><p>But technical problems denied them their fuel economy goal of 678 miles per gallon (288 kilometers per liter), which would have broken the previous Shell Eco-marathon Americas record for diesel vehicles. Instead, they ran at 378 mpg (161 km/l) and received a special award for safety in vehicle design, construction and onsite behavior. They also were able to cheer their schoolmates, as a second team from Granite Falls won the $1,000 first prize for diesel energy vehicles with their entry in the challenging "urban concept" category for autos that meet safety criteria for driving on city streets.</p><p>At opening ceremonies Saturday, Shell executive vice president Bruce Culpepper foreshadowed the weekend's ups and downs: "We know that the path to success is littered with frustration, failure, broken parts, and sometimes even broken hearts," he said.</p>