Unveiled at the 1993 Tokyo Motor show and now is on display at the Mazda Museum in Hiroshima Japan, the HR-X2 concept car featured a Hydrogen rotary engine. This car adopted metal-hydride to carry hydrogen fuel safely. Although range was only 150 miles a tank full it was considered a breakthrough with the new hydrogen fuel. The range was affected by the level of safety equipment required to transport the explosive fuel. Performance was as good as a normal family sedan. The body was also an environmental wonder with all of it being recyclable.