Challenge X: Crossover to Sustainable Mobility, known more commonly as Challenge X, is a four-year competition series amongst engineering students from across North America. Its purpose is to advance vehicle technology towards a goal of sustainable mobility. The headline sponsors of the competition are The U.S. Department of Energy (DOE) and General Motors (GM), and the competition series is managed by Argonne National Laboratories (Argonne). Team evaluation, technical and logistical support is also provided by Argonne. The 2006 – 2007 academic year is the third year of the competition.