At long last, the team achieved a breakthrough in 1963, when an engineer proposed the idea of changing the apex seal’s frequency characteristics by modifying its shape. A cross-hollow seal with a cross-shaped hole near the apex of the seal was developed and tested. The test proved successful, with no chatter marks appearing on the inside surface of the engine. In the following year, with the support of Nippon Carbon Co., Ltd., Mazda created a new apex seal made from aluminum-carbon composite materials. This innovation opened the way for bringing rotary engine-powered cars to the street.

The Cosmo Sport was Mazda’s first rotary engine-powered car. Designed right from the start to be driven by a rotary engine, the Cosmo Sport featured an unconventional styling that created a buzz.

Before the launch of the Cosmo Sport, trial rides were organized at car dealers across Japan to evaluate the new car’s performance, at the suggestion of President Matsuda. “With the cooperation of dealers, we will be able to obtain practical, useful data. If we fail after coming this far, it will be said that “the rotary engine is useless.” That would be regrettable,” Matsuda said. As problems reported from dealers were resolved one after another, the engine moved step-by-step closer to commercialization.

On May 30, 1967, the Cosmo Sport was premiered, marking the debut of the world’s first mass production car powered by a two-rotor rotary engine. That was the moment when the Mazda samurai’s resolution and tenacity as well as their innovative ideas came to fruition.