Freshman mechanical engineering students at Johns Hopkins University in Baltimore, embarked on their first major design project, which required them to construct model cars that self-propel without the use of a motor or a battery. The source of energy? Six rubber bands and two mousetraps.

To make it more interesting, the cars were then put to the test by racing one another on an 11-foot long s-curved slalom course. That’s right, s-curved, meaning the cars also were also required to have their own self-guiding steering systems. “With rubber bands and mousetraps as their on sources of power… the students to have to combine the different degrees of freedom of their engineering system,” said course instructor Allison Okamura, an associate professor of mechanical engineering. The project focuses on principles such as potential and kinetic energy, friction, and material properties.

The competition involved 20 student teams using everything from balsa wood to foam to wire hangers to build their vehicles. But, of course, the most impressive aspect was the battery-less powertrain. The ultimate testament to sustainable mobility.

Hybrids, clean diesels, and fuel cells ought to step aside. They have nothing on rubber bands and mousetraps. Check out this cool little video that shows the event: