The winning team, from Cornell, used a fuel cell to generate DC current that powered a Lego motor. Other fuels this year included candy sours (citric acid), beetle liver (catalase enzyme), and fire starters (magnesium). The race's twist is that the car must also stop using a chemical reaction, and the closer to the finish line it stops, the better. The Cornell team is the first in history whose vehicle stopped directly on the finish line with a braking system made from an Iodine solution and a light sensor. When the solution turns dark, the light sensor triggers a circuit switch so that the power that had been driving the motor instead lights an LED.