Challenge X was a multi-year advanced vehicle technology competition run by the U.S. Department of Energy and General Motors in the mid‑2000s. It challenged university engineering teams to re-engineer a Chevrolet Equinox to improve fuel efficiency and reduce emissions while maintaining performance. The program was primarily targeted at undergraduate engineering students, not high schoolers, and is no longer an active competition. While sometimes referenced in discussions of interdisciplinary STEM competitions, Challenge X itself did not operate as an ongoing high school extracurricular program. High school students mainly interacted with it indirectly—through outreach events, demonstrations, and exposure to its engineering concepts—rather than as direct competitors. Today, its legacy lives on in successor DOE–GM programs (like EcoCAR) that continue promoting hands-on, interdisciplinary vehicle design experiences, typically at the university level. For high schoolers interested in similar interdisciplinary STEM challenges, it’s more appropriate to look at current programs such as FIRST Robotics Competition, Science Olympiad, or other energy and engineering design challenges that explicitly accept high school participants.