Mazda formed a relationship with the NSU cpmpany who were using Wankel rotary patents to build the Rotary type engine for commercial use. Mazda completed their Cosmo Sport which was completed before NSU's offering. The Rotary engines advantage is that it offers great power output for minimal weight, with its downside being increased fuel consumption. The 1973 fuel crisis nearly broke the company as they had to rely on their smaller piston engined models sales (Familia and Capella models). The Mazda MX5 continued as a piston engined car, but their huge investment in R&D for the Rotary engine led to returning in 1978 with a more efficient Mazda RX-7 and later RX-8 models.