1969 Mercedes-Benz C111-II

Neither the C111-II or C 111 did not to appear in showrooms despite their lavish interior and cargo space. 
The coupes may have looked production worthy, but complex technologies embedded within in the cars kept them as experimental cars. However, the research in testing Wankel engines, new suspension components and plastic bodywork components contributed to future Mercedes-Benz products.
Subsequent versions of the C111 project were powered by a diesel engine. Mercedes-Benz successfully showcased their prowess by breaking many world record with diesel powered C111s.