The rally ran 180 miles (290 kilometers) from Berlin to Hamburg, Germany’s second-largest city. Organized by a coalition of auto and energy companies, the idea was to convince the German public that hydrogen will be a viable, green fuel source for cars, buses, and trucks.

It’s all part of an ambitious effort to build support for a network of hydrogen fueling stations across Germany. Called the Clean Energy Partnership, the group hopes to have more than 1,000 fueling stations in operation by 2020. Since it began in 2002, the CEP has grown to include 13 companies, including automakers BMW, Daimler, Ford, GM, Volkswagen, Toyota, the Berlin and