The document summarizes the history of hydrogen rotary vehicles developed by Mazda, beginning with the HR-X prototype unveiled in 1991 that had a proposed 125 mile range. In 1993, Mazda modified a 3rd generation RX-7 engine for hydrogen and installed a large multi-tubed hydrogen tank in the trunk of a modified Miata. In 2006, Mazda introduced a dual fuel RX-8 that could travel 60 miles on hydrogen alone. Mazda's 2009 Premacy hydrogen prototype was a modified RX-8 with front-wheel drive that could seat 5 and had ample luggage space, traveling 120 miles on hydrogen alone. The document explains that rotary engines are well-suited for hydrogen due to their